>And what's the difference from the US government when it wants a bigass factory?

A normal business transaction, with all the good and bad parts thereof. The government can't force the issue unless they do it themselves which is usually not the case.

not just that, but the fact that the US gov't does hold elections means that what they do generally is in line with the people.

At this moment, what the chinese gov't is doing is _also_ (presumably) in line with their people's wishes - after all, factories and exports means jobs and economic growth. It remains to be seen if this continues to be in the face of a potential war, tariffs, or some other external shock.