"At the end of the day this devolves into tariffs"

No not really, you boil it down to that, but that's simply your framing nothing more. There's also the regulatory environment, so no it's not all about tariffs. There are almost no environmental controls or labor laws in China. So that is a huge factor. There is equal or more possibility that companies wish to avoid the responsibility of ensuring compliance as they do with merely avoiding taxes.

"If you want fat, state protected corporations then fine"

How does restricting the supply of unskilled labor from illegal immigrants and border crossers, visa holders of various stripes have anything to do wit fat protected corporations?

I agree that we need to harmonize regulations for trade, but guess what? We're already doing that and the Chinese are responding by getting cleaner so they can compete in more areas. In fact the US is one of the most pollution-heavy developed countries, so if anything the US is exploiting our shared global environment.

The reality is that, globally, there is a low skill labour glut because most countries are only now developing advanced education systems. If you want to stop competition from low skill labour you ultimately need high tariffs or extreme mechanization / automation, neither of which are good in the long run for poor people here.