Honestly, the more I think about the "added details" that TNG provided about Earth's 21st Century, the more I just want to scream.
I'm not a "Rodenberry's VISION" guy by any stretch, but I have always believed that Star Trek's most precious message is that we survived into the future without dropping nukes on each other and by our own efforts and gradual growth.
Instead, we've got a legacy of thermonuclear war, the "post atomic horror" and the fact that we couldn't get our shit together without aliens helping us.
I don't know....it always bothered me. It kind of takes the magic away from what Star Trek was originally trying to say I guess.
Well, Roddenberry's earliest contribution to that was "Omega Glory" where the claim was made that Earth dodged the nuclear bullet. But that one only aired after "Bread and Circuses" where "Roddenberry Trek" established that the first three World Wars were just for starters... And the post-atomic horror came straight out of Roddenberry's own pen.
Both in-universe and backstage, we're hard pressed to find a period of time when Earth being nuked to bits by us stupid barbaric Earthlings would not have been a thing. Although TOS sort of pushed the idea that those barbarian genocidees were romantic figures and affable tyrants and whatnot, while only TNG made everybody from before 2161 a knuckle-dragging and drooling not-so-great ape.
He said there were "very few" governments left. He didn't say there were none left.
The USA was one those that survived the war. We know this because the war took place in 2053, yet in a TNG ep there is a US flag with 52 stars on it, and somebody says this places the flag as coming from anywhere between 2033 and 2079.
I initially thought that humans fought and fought and maybe there was a nuclear exchanged that finally convinced humans to change for the better.
Until the destruction porn set in. The Eugenics Wars that seemed like WW3 in TOS that was seemingly downgraded and replaced with another WW3. Then the Eugenics Wars seemed to get downgraded again in Voyager--they time traveled to earth in the mid 90's and there's no mention of it.
Then the weird version of WW3 in Encounter at Farpoint that made it look like humanity got it bad. Then WW3 from First Contact that has the US in tact--sort of. They're experimenting with warp ships and drinking in bars.
It became such a mess instead of keeping it relatively simple.