The DDR aka East Germany ended in the 90s, and the Franco regime in Spain ended 1975 with Francos death.
It is debatable if one should also count the Yugoslavian/Serbian government which existed until the mid-90s as oppressive - I certainly do, Miloševic rot in pieces.
Oh, I almost forgot the rest of the Soviet block... so you basically have oppressive regimes as low as 20-30 years ago, leaving a LOT of people with first hand experience.
But typically, the sort of people who blithely compare the US to a police state do so by invoking the Nazis. I wasn't going to credit such arguments with that much subtlety or self-awareness, since they seem to come from a sense of prejudice and knowledge of pop culture rather than history. Although you're right - there are a number of recent police states and dictatorships which the US does not resemble.