As someone who grew up in the 2000s I still don’t get it. I grew up in a time when this was totally fine and normal. I cannot imagine being so restricted as a child.
Osama may be dead, but the erosion of rights that US has seen because of 9/11 did strike a big blow to US democracy and he partly achieved his goals.
I could totally see the trend being accelerated by a lot of things. Sure, 9/11, is one possible trigger, but it could also be news sources getting better at optimizing for sensational takes and - more recently - the common person using the internet/social media to amplify troublesome anecdotes to the point where they seem like pervasive trends.
Which, of course, describes this entire thread of discussion kicked off on one person’s anecdote…
America lives in constant fear of everything and it only seems to be getting worse.