Except when it doesn't. As in Star Trek 4, where Earth is just as it should be, minus the race of genetic supermen dictators that should have already been in charge for any of that stuff to make sense.
It doesn't matter, I just like to laugh at the weirdness of it all.
It's the beauty of near future scifi. Set your story in the near future, and everyone gets to have a laugh when the time comes.
Nah, the eugenics war was in the 90s.