I have volunteered at a couple of different food pantries, and I have to tell you: fraud prevention measures raise the percentage of scam and abuse. "Fraud prevention" doesn't eliminate fraud, it raises the percentage of fraudsters who get help. Let me explain.
I used to volunteer at a food pantry that got some of its funding from a government program that required means-testing. That means, we were required to get paperwork from every person we served that they were genuinely poor enough to need help and qualify for it.
So when they came into the building, the first stop was a large room with 8-12 volunteers (depending on the week), who had files and files full of paperwork that they were required to update every time someone came in. The first time someone came to us, they had to have a bunch of documents--and despite a lot of outreach and publicizing, we would inevitably have people who came with some of the documents missing or the wrong documents. A lot of people simply didn't have the documents, because people on the margins of society often have problems like being thrown out of their housing for one reason or another (fight with partner, evicted by landlord, etc). Once you had the paperwork on file with us, you still had to check in with the paper-pushers every time you came to the food pantry, and then every so often (I think yearly?) you had to update your paperwork to prove you were still poor enough to "qualify" for help.
It was a lot of work to check all that paperwork and check people in and all that stuff. Even with 8-12 people working in that room, and even with most people already on our books and thus having a file already, so they only needed a few minutes to check in, there was always a long line of people waiting.
Once the paperwork was (finally) done, they'd come down the hall to the room with the actual food in it. There were usually 3-4 volunteers working in that room, and the clients would come to the door, hand one of them a slip of paper with the number of people in their household, and get handed a bag of food.
The paperwork took 2-3 times the number of volunteers, and at least ten times the time, as the actual distribution of food did.
And we regularly had people come looking for help and walk out defeated by the paperwork. Maybe they couldn't get the papers. Maybe they didn't have time to wait--they had a job to get to, or kids needing them, or their ride had a job to get to. Or they just got frustrated or humiliated and decided that it was better to go hungry than put up with that shit. Sometimes they left in tears. All that paperwork, all that effort to root out fraud and abuse, it regularly turned away people in genuine need.
You know who had all the time in the world to fight their way through the bureaucracy?
The fraudsters. The grifters. (And we did, very very rarely, get one.) They would take whatever time it took to get what they wanted.
Means-testing didn't prevent them from getting help. It did prevent genuinely needy people from getting help. And, bonus, it required 2-3 times the number of volunteers, and also required more paid government bureaucracy to handle and process the reports.
Any measures you take to prevent people from abusing the system will inevitably increase the percentage of fraud (by driving away people in genuine need), and also make things vastly less efficient and more expensive by requiring lots of people to handle the bureaucracy.