I think you're overstating the obviousness and up-frontness of crime in most of the US. I can't recall the last time I "witnessed crime" out and about here in America. Public urination or something a few years ago, probably. Or littering more recently, though you mention it separately. "I didn't witness crimes in a year" doesn't sound exceptional.

Yelling or mental health issues, sure, there's a different culture there in America, but "loud vs quiet" as a cultural different doesn't seem like a major moral issue, and it's well known that the US is handling mental health poorly, so sure, I'll give you that.

But then on the flip side, Tokyo is also notorious for public-but-sneaky sexual assault, no?