For all the other differences in culture, the attribute of "People Actually Care" seems to have a huge impact on how pleasant a place it is to visit or live.
I don't know why it seems to be the case there. I don't know how to replicate it. I don't think it's magic. I've heard people bandy about the theory of cultural homogeneity. That might be a _factor_, but I doubt it's the full story.
I suspect if you dig into it, differences in economics are a major factor. In the US, it feels like caring is actively punished, economically. Caring is nice, but someone can only _afford_ to care if their other needs are met.
I also wonder if density is a major factor - not so much for the difference in economy of scale, but the difference of "if my physical space is incredibly constrained, I'm both more incentivized to keep it looking nice, and there's less of it to keep looking nice."
And, of course, it's not like Japan is some kind of otherworldly utopia. There's serious tradeoffs and differences, there's negatives compared to other countries. But it does seem like almost everyone, everywhere, just... puts in a bit more effort. Takes a little bit more time.