I think "don't want" isn't the right way to look at this. We "want" China to build all our stuff because it's cheaper, and it's cheaper in part because China doesn't care about pollution, so energy costs are lower. (Cost of labor and other factors of course also tie into that.)

If China were to put strict, California-style controls on pollution, energy generation would get more expensive there, and goods made in China would also get more expensive. That would be an incentive for other countries to manufacture more of their own goods (or find a new, cheaper country to build things in), and certainly China does not want that, so they continue to pollute.

We want cheap stuff above non-polluting stuff, so we make them do the polluting. If we really cared about pollution we would put a stipulation that the stuff is made a certain way, and we would send someone to actually check this. The way it's done now there's a wink and a nudge, and the Chinese know perfectly well what the deal is.

Note that labor would still be cheaper there, so we could still have cheaper stuff, we just want it even cheaper, to hell with the consequences that we don't see anyway.

It's not just energy either, there's various chemicals and safety concerns that people discovered in the west a long time ago. It's just that the allure of cheap stuff is so great, it was fine to just stop making it in the west and pretend that standards overseas were acceptable.