The idea that amity is causing an economic collapse for the rest of the nation is hilarious and i love it, but idk how likely it would be. I think you're underestimating just how big america is, and how fucked its economy already is. (Though perhaps things are run better in a world where being a corrupt politician/elite comes with the risk of being investigated by the justice league, whistle blown by lois, and then hospitalized by batman just for good measure.)
Im autistic and have managed to keep a credit score of zero, so i dont know a lot about credit cards, but my understanding is that credit cards here have a limit thats determined by your credit score, and if you go into the bank to get a credit loan (slightly different from a credit card, but usually called the same), they also look at your income and assets. As far as im aware, like debit cards, if the card goes over the limit, subsequent transactions fail (and you get a big fee). Or maybe they dont fail because debt slavery is a concept that lots of americans don't understand, and credit companies ruthlessly exploit? Idk.
Now, i dont know if this happens in other countries, but here we have an epidemic of credit companies mailing out filled forms for extremely high interest rate credit cards. Entire lawsuits have been had by people being threatened by creditors for debts in their name they had no knowledge of because mail thieves got the forms, and literally all they had to do was forge a signature for free money.
This whole system is automated. So, while individual cards have a limit, amity parkers could theoretically get an endless supply of cards. Though i imagine the amount of junk mail they get will taper and fall over time as automated systems are increasingly updated and amity's addresses are corrupted, lost, and forgotten. That transition to move everything to the APDC address probably caused a huge decrease as well. Its also possible that the computer program running the mail-scam credit cards is sophisticated enough that while people have forgotten amity, the algorithms still know the location and is tracking transactions, seeing that payments arent being made, so less cards are sent as financial risk (for the company) increases. Again, Idk.
In this situation, anything Parkers buy IS getting paid for - the credit companies are the ones losing the money because they aren't being paid by the card-holder. This WILL start an investigation, and with how crazy the dc world is, i wouldn't be surprised if magic-based private investigators are a legitimate niche field for particularly mind-whammy cases. They would recognize and counteract the perception filter, at least for themselves, and figure out what was going on. Then, they would probably just advise the companies to take all Amity Park addresses off their systems and cancel all Amity Park cards. Still, that'll take time, so AP probably has a few months or years of free reign before being cut off. Perhaps its what allows them the money necessary to set themselves up as self-sufficient?
Why can credit companies get through but not the IRS? A number of reasons. First, my handwavy excuse that danny's reality rewrite was targeting the government, so the government gets hit the worst. Second, the responsibility of taxes largely falls on the person paying the taxes, which, again, out of sight, out of mind. Third, in the cartoon, the GIW wield the threat of auditing taxes for comedic effect. But if the entire town is declared non-sentient, why expect them to pay taxes?
Fourth, let's say a couple of magic investigators working for the IRS get through the filter. They harrass a couple of Parkers and the Parkers' response? The government doesn't recognize their town exists, has stopped paying for infrastructure upkeep, has cut off their banks, has forsaken their schools, and on top of All That, created an entire branch of the government to hunt them like animals because their people have been legally declared non-sentient. If they were to kill them and leave their dead bodies out in the open on main street for everyone to see, nobody from outside city limits would remember they even existed, let alone come looking for them. (The same warning is given to the credit companies' debt collectors, and the credit cards start getting canceled shortly after that.)
Last, if Amity Park is claimed as part of the Ghost King's domain, the US legally can't demand taxes from a foreign nation. (That would devolve into a huge argument over the sovereignty of the ghost zone and their right to claim AP, but it could only be started if enough people on the outside can remember long enough to actually contest the claim, and how much influence giw has when they discover that their sworn enemy has stolen an entire city from their nation - and even made them forget.)
Regardless of whether the credit companies deliberately cut them off or the cards naturally expire (and they stop getting new ones), afterwards, Amity Parkers have to go out of town to get loans and credit, which is a hassle when large swathes of their financial history cant be found as Amity is increasingly sectioned-off from the rest of the world. It's just another reason to remain in Amity and become self-sufficient.
However, i like the idea of various perception-filter-immune individuals (magic users, supernatural creatures, god-blessed, maybe a few metas and psychics, etc) stumbling into Amity and all its bat guano crazy. Amity Park's forged document industry absolutely explodes in growth. It's an in-broad-daylight market with competing businesses and legal regulations and protections because it's seen in Amity Park as a legitimate and necessary commodity. All these people living on the edges of society to hide their strangeness now have a way to participate without drawing attention. The black market for forged documents nationwide is collapsing as those immune to the filter introduce those that aren't, and nobody in the business can quite puzzle out why.
OTOH, crime might increase as fugitives running from the law seek refuge in Amity Park's perception filter. Sure, some of them are running from discrimination, but most will inevitably deserve their fugitive status and start causing problems - right up until phantom puts his foot down and proves exactly *why* he's top dog. Amity Park would probably treat the situation as not that different from when the portal first opened and most of the new visitors were trouble makers until phantom established the status quo.
Onto the CAT - it was absolutely a parody of standardized testing, and the idea that lancer would just have the answersheet on his on his person at all times is laughable. I supposed one could argue that clockwork orchestrated a series of events to make it happen, but it's definitely not realistic.
The two main standardized tests in the united states are the SAT and ACT, which are designed for college admission. Many states also have standard tests for their schools to benchmark progress at certain grades, which is what the CAT probably was, given that danny is a high school freshman. Here's a link:
https://educationadvanced.com/resources/blog/list-of-standardized-tests-by-state/
My understanding is that the tests, once complete, are mailed to the committee that created the test for grading, and the summary of results are mailed back to the school, but in my 5 minute quick dive, i couldnt find anything to verify that, and its very likely that different states handle their tests differently. I also discovered that this is the first year that the SATs were taken digitally instead of pen and paper, so that's another level of automation that parkers can exploit.
As for birth certificates and missing persons, i think most of that problem could be handled? Again, Amity Parkers working in neighboring hospitals know that the patients are going home safely and getting regular checkups. Idk what all kind of details go into hospital records outside of legal documents and history of appointments (for billing and health records.) Would hospitals actually record that such and such baby was assigned to such and such doctor for check ups? Idk if that kind of record would exist in order to collect statistics. If it does, then the Amity secretary is the one writing up the records and filing them correctly. Perhaps 'correctly' includes the information that the newborn was moved to Amity General Hospital, Go Look There For More Information. (After all, all Parkers are liminal, and AGH specializes in liminality.)
At the very least, a record of the baby's existence is available, and all the neighboring hospitals would have at least one Amity secretary to handle Amity related appointments, records, billing, etc. Hospital administrators are aware that a perception filter exists that complicates treatment of some of their patients, from... where was it? Oh yeah, Amity Park. Local hires are necessary to keep things running smoothly. All questions regarding the Parkers get directed to That One Secretary. They can answer your questions.
Working with Amity Park pretty often means it doesnt quite fall into that 'out of sight, out of mind' category, (a lot of people in neighboring cities are gonna have family in AP after all, and it was never Danny's intent to make any families forget each other) and the staff have gotten good at recognizing when the filter is screwing with them and know to seek out That One Secretary to help straighten things out.
To be honest, i was actually imagining that the babies and such are actually being born in AGH, but the hospital calls one of the neighboring hospitals to essentially outsource the creation of the birth certificate and ssin, providing the pertinant info. The calls and subsequent record creation are like 90% of the work that the amity secretary does at that hospital (any records, not just birth). The parkers that go to neighboring hospitals only do so because they need that particular hospital's specialization for treatment, and their liminality and the effects it might have for that particular treatment are encoded and treated as meta powers. Honestly, this set-up might only last until enough ghost doctors are hired and AGH is expanded enough to handle literally anything, as an increasingly liminal population means that in more and more cases, the liminality of the patient effects treatment in a way that the other hospitals cant account for.
In other words, looking at the hospital records would show a few things:
AGH stopped handling all childbirth, all amity parkers converted to at-home delivery, and unfailingly send the forms for birth certificate requests to neighboring hospitals instead of APG. (Babies are actually born in AGH. Looking up the doctor responsible for their delivery shows that they're employed at APG. I think labeling as at-home delivery would be easier than porting and forging records that they were actually at the neighboring hospital.) This is Really Weird, but anyone who is able to investigate this far already had to overcome the perception filter, and a few questions asked is enough to figure out that the situation screws with legal processes. If they can't get past the filter, they just see an increase in birth certificate/ssin creation in surrounding hospital records, and the statistical anomoly disappears if you discount Amity Park address, so its clearly centered... what were we investigating?
Amity park must have had a recent mutigen event (like dakota city, or central city in continuities where the collider activated everyone's powers, etc) because nearly every amity parker is now listed as a meta in the neighboring hospital records. If they get past the filter, they'll find the AGH records use the term liminal instead of meta. If not, something clearly changed in the greater illinois region, but nobody can really wrap their head around what could have caused the statistically higher percentage of metas from illinois.
After a few years, it becomes apparent that Amity Park's death rate suddenly dropped way lower than neighboring cities (according to the number of cases taken on by the neighboring hospitals). It isn't difficult to connect this to the suddenly meta population, but it's gonna garner interest, much of which will NOT be good. A mutigen that causes extended life/immortality is gonna make a lot of people go crazy for answers. (Maybe AP life expectancy has actually increased, but largely a lot of ghosts are just choosing to not legally report their own death.) Since Amity is under the perception filter, whoever finds out about it is able to harrass Amity without any other outsiders knowing, BUT they themselves have to have worked past the filter as well. It's definitely a double-edged sword.
There is a slow decline of Amity Park patients in surrounding hospitals (as AGH can accommodate more situations and liminality becomes the most important specialization in more cases), even as AP birth rates continue to exceed (or match, if the investigor can see than there are no birth records in AGH) surrounding towns. The ratio of AP birth certificates, death certificates, and other cases in the neighboring hospitals is wildly different compared to any other towns they serve. Birth certificates are way up, death certificates are way down, and the number of patients is declining despite apparent explosive growth in Amity.
If they can see AGH records, there are zero births (but a lot of patients refered within minutes of birth), exceptionally low deaths, and nearly all cases are associating with complications of liminality, which entirely replaces the term metahuman. Statistics for injuries (especially from car accidents), health defects, complications of health decline, cancer, etc are all suspiciously low, as liminality increases durability and decreases recovery time and seriousness of the injury (higher threshold of damage before checking into the hospital means overall fewer cases.)
A new category of health record has also been created: legally alive but biologically dead - ghost health needs are different from a human's after all. Parkers are encouraged to schedule a doctor appointment as soon as possible after they die so they can update their records to reflect their changed needs.
Word gets out, slowly but surely, that an american city hidden from the world exists under a perception filter. Knowing its name makes you forget about it. Most people treat it like an urban myth, but the supernatural populations are suddenly immigrating in large numbers to live in such an accomodating and friendly city. It freaks out the magic users a bit at first, and I'd imagine it only takes a couple of years at most until JLD hears about it, but idk if they would tell the Justice League or not. If Constantine is the first to discover Amity, would he even share with the others at all or keep it to himself?
