Apparently, this is changing: https://www.tsa.gov/travel/security-screening/identification...
Similarly though admittedly more permissive, with Amtrak iirc it's like: you need a credit card and they probably won't check your ID. There were several more years after 9/11 before the "papers please" principle came for the trains and buses too.
E.g. search turned up a claim Greyhound "employees are not allowed to sell a ticket without an official ID" https://travel.stackexchange.com/questions/140703/i-have-no-...
You definitely need ID for hotels a lot of the time. Not sure the level where the regulations are put in place--probably varies--and Europe is probably more formal than the US in this regard. Was staying with a friend in Europe about a year ago and they had to take our passports to the police station to make us "official."
As I wrote elsewhere, I also had a challenge in the US a few years back but I expect that, had I been at my usual chain, there would have been a discussion with the manager followed by "I see nothing, I hear nothing."
ID is not security.
This conversation just doesn't seem promising. Your initial wildly-off claim got me worried I might misunderstand the world by that much (I remember the 70s, fuzzily). I wasted time checking it, wondering if the actual peak might be in a year not mentioned, trying to find the paper Wikipedia cited: it was a non-open-access paper with at least four links to check; one of them did show the first page, which at least gave the figure in question, if not the ultimate source.