I think a big part of it is that too much time has passed since the last bunch were dealt with. Most people who remember that are dead now.

It's also an education problem. Instead of "yay we're the good guys, we beat the bad guys", there should have been more understanding of how the bad guys got so bad, and why the USA always had the potential to go down the same road. But if you're looking at it on a superficial level, you can think you're automatically safe from that, just because you have different names, different locations, different flags. And because you're the good guys.

Don't forget the ACLU protecting Illinois Nazi hate speech.