This is an observation about the world in general, not U.S. politics specifically. Prosecuting elected officials basically means that you trust the bureaucracy more than voters. This has not proven to be a successful approach.

We have been very lucky in the U.S. to avoid these problems. And it's not because nobody before Trump ever did anything rising to the level of paying off a porn star and calling it "legal expenses." It's because we have had a taboo against prosecuting politicians.