Small nitpicky correction, but in China, city tiers are designated by policy and generally correlate to the quality of life for the middle class there. The US doesn't have a tier system. If it did, it wouldn't make much sense because the quality of life in American suburbs and exurbs is generally better than the most developed cities (unless you're rich, of course).

Free, clean toilets are everywhere in America, just not in the dense city centers (walkable, transit-oriented, mid-rise or higher) that people tend to visit on vacation. I'd estimate only 10-15% of Americans live in these city centers, whereas in China it's probably closer to 50%. With the raw numbers, this difference shouldn't be underestimated.

> I've seen much cleaner toilets in first-tier China cities than first-tier US cities.

That definitely tracks. LA has a massive unhoused person issue, many of whom with severe mental disorders. You feel a lot that in the commons, especially as you get near DTLA. New York is shabby and dirty in general. More so than a big city usually is. And it's not really a charming shabbiness from an extreme subtropical climate as you get in Taiwan.

The relationship China has with its tier 1 cities is more similar to other Asian countries, like Japan and Korea, than it is to the US.

Chinese first tier cities aren't accessible, you can't even live there as a country bumpkin.