Yes, the rest of the world got the extra security restrictions in order to fly. I'm in Europe and we generally have better, faster rail networks than the US (and everything is closer together) so we don't fly as much as Americans.

I used to work in the US about 10 years ago, and the contrast between that and when I visited in the 1990s to go to Graceland is pretty stark. It takes forever now to get through those TSA queues and immigration. You could also smoke on the transatlantic flight in the 90s!

Depends I guess, it was by and large, but as I understand contemporary intra-US flights are much more fussy than intra-EU ones.

Airport security inside the EU varies, they will make you go through the detector gates and X-ray your baggage, but they don't care much as long as you are not bringing weapons or something. Amsterdam Schiphol let me through with a half-empty 2 liter bottle without me noticing, the security on the back trip caught it. I've traveled a few times outside the EU, but it was also pretty automated, the only extra step was getting in a separate line if you had an EU passport, since they had NFC chips that would make checking them automatic.

Security in general mostly takes 10 minutes, if everything goes alright you can make your plane even if you get to the airport 30-40 minutes before departure. It does not go always alright, so I try to arrive 60-90 minutes early. Leaving the plane is no fuss, I usually get away with calling a taxi right as I deboard and I don't stop anywhere getting out. I've flown planes without assigned seating as well, the pilots put the baggage in the hold themselves, it was kinda like a long distance bus.

You can't wait at gates, that's true.

That said, airport security changes are pretty down on the list if you count the implosion of the USSR, the Yugoslav war, Georgia, and a bunch of other stuff happening kinda near it. From this side of the Atlantic, it feels it was only a big historical event because it shattered a perceived "invincibility" of the US. It never really fought a modern war in this century or the last where it was actually risking something other than expeditionary troops, mostly thanks to geography.

Generational trauma from WWII is still a thing today, imagine the effects of historical events since, and it kinda puts it into perspective why a few thousand people being bombed on a distant shore has people maybe even more indifferent to it than people in the US are to events everywhere else.