I don't believe I have ever, and I do mean ever, met a person irl who cared enough about the "Uyghur genocide" to mention it if I'm (lightly) glazing China.

There was a post on here a few months ago about a university professor who legitimized the idea in class, even going as far as saying that Uyghurs were not considered a real ethnic group in China (basic, bottom-of-the-barrel lie that even a half-second of research would have contradicted).

so... why and how can China, the "inferior" nation, build high speed rail across their massive country but the mighty US can't? Shouldn't we do it too just to prove we're number one?

The problem with trying this is that the reasoning doesn't go from considering national accomplishments to determining superiority/inferiority, it's actually the other way around. National status is predetermined through a series of racist tropes and everything else is viewed in light of that. China isn't superior because they can build high-speed rail, the HSR network is actually a totalitarian means of 1984 big brother control because China is inferior. The US isn't inferior because they can't build HSR, our inability to do so reflects our spirit of freedom because we are superior.