[as a heads up, this got very long - sorry!]
generally speaking, a lot of cultural things like this just get forgotten because it's not what we learn about in basic history classes. unless you specifically pursue looking into a subject like the history of courting, it's not what comes up in a typical history textbook, where we tend to learn more about the broad strokes of history. plus, terms like "hookup culture" and "courting" tend to just enter common usage, stay there, and rarely get defined because everyone knows what it means. with modern terms, we do have stuff like urban dictionary where people intentionally define "slang" (mostly AAVE, tbh) and other "newer" terms, and i know merriam-webster tries to catalogue new words/terms as well. though once all this digital stuff disappears, that'll be a different problem for future archivists and historians, of course.
but, the main point there is that people don't tend to define common terms when talking to others. with the point about the dad (and others) who thought hookup culture and cruising culture were largely the same thing, this is because we generally assume that if you're speaking the same language as someone else, you're both using words the same way. unless you're using something like a specific academic term in a specific educational context, or have some other reason that you'd be expected to need to define a term, it's just... not really done. this is a huge part of how miscommunications in general happen, by the by - how many times has someone said they'll be there "soon" and you assumed they meant in the next five minutes, but they meant in the next half hour (or vice-versa)? connotative meanings are kind of a bitch, that way.
there's also the fact that people just... don't like to talk about things that suck. let's pretend, for a moment, that american culture did have everyone living with their grandparents, all the way from the pre-war era to today, with no "nuclear family" period. my (known) grandparents were all born in the 50s, and their parents were born in the 30s. so their grandparents would have been kids during the Great Depression, and their grandparents and parents were likely all involved in the war effort in some way (i know for a fact that my great-grandparents on my maternal grandpa's side were, in fact, a merchant marine and a navy nurse, which is how they met).
so my boomer grandparents would have been born towards the end of the economic boom, and spent their childhoods and adolescent years watching the economy slip and fall down and down. my grandpa was rich, and probably insulated from a lot of that (plus he's older, so would have known more of the post-war boom first). my grandma on my dad's side, though, was born in the late 50s to a poor family, and they would have struggled a lot as the economy got worse. do you think my grandpa's parents wanted to tell him about how bad things used to be, when things were going so well now? and do you think my grandma's parents wanted to scare her with tales of how things used to be worse? and i did actually live with my grandma for a few years growing up, and she also didn't want to talk about how bad her childhood was. neither did my parents, for that matter. most people don't like talking about things like that, especially with kids.
so the only way to learn is to intentionally pursue the information - ask and hope you get a straight answer, research, take classes.
now, all that being said, when it comes to american culture in the pre-war and post-war eras though, there was also a concerted effort to push a significant culture shift after WWII. during the war, a lot of manufacturing jobs and other industrial positions were taken over by women, because the men were off fighting. when the men came back, they wanted their jobs back, but we also needed way less manufacturing (since we were no longer building tanks n shit). so not only were the jobs that existed occupied by women, there wasn't exactly room to make more jobs for the men. so there was a big push towards stricter gender roles, lots of media featuring housewives, and all that jazz. the same way rosie the riveter was used to encourage women into manufacturing jobs, media images of femmed-up housewives was used to get them back out.
the family structure thing was sort of rolled up in this, too. the original GI bill promised low-interest mortgages to WWII vets, which caused a push for houses to be built fast and cheap, which was a huge part of suburbanization. it was a very brief economic boom in which a lot of families could afford to live on a single income, with a stay-at-home housewife/mother, and people didn't need to live in intergenerational households anymore. having more households buying more stuff - e.g. now you, your parents, and each of your siblings all live apart, so you all need a fridge and an oven and a vacuum and and and, instead of all sharing one - was great for companies, so they pushed the image of a single-family suburban household as âšThe American Dreamâš
i could honestly talk about this for hours, and would be happy to add more info about the post-post-war period, but the relevant bits here are that the economy did not stay Stable And Amazing Forever, and once you get into the 50s and for sure by the 60s, that american dream wasn't achievable for most folks anymore. but companies still really like it, because like i said, it makes it so more people have to buy their stuff, so it continued to be the dominant media image for some time. "working moms" became a thing once it was clear that single-income households just weren't feasible for the majority of people anymore, but with that came a class divide of women who could afford to stay at home vs. women who needed to work to support their families, and the idea of a family having a stay-at-home mom became an ideal to strive for instead of an assumed reality.
