Well there is obviously a reason they dont do it, or you would see them doing it. Its just finding the reasons why at this point.

They should. How will the UN make them?

In this case, the CCP also provides massive subsidies to them. If they did not build in China, all the money would dry up

They would stop being cheap if that were the case. They are able to build competitively in China because of huge government support. Building Overseas, they would become just another car maker.