It's not that simple.
China has supported key industries (like EVs, batteries, solar, semiconductors) that it views as strategic. Each country should do the same for their own situation. There is no such thing as pure capitalism- and what you see is 'protectionism' is to a lawmaker a way to ensure that the local company survives and provides jobs for the local region/state, etc.
And as the other commenter mentioned, auto manufacturing plants were retooled to make tanks and jeeps in WW2 and so no country that cares about their own military survival should cede auto manufacturing to another country, let alone China.
> China has supported key industries (like EVs, batteries, solar, semiconductors) that it views as strategic.
https://en.wikipedia.org/wiki/2008%E2%80%932010_automotive_i...
We did too, but we didn't effectively hold any of the executives or financial planners liable for the terrible direction domestic auto companies had gone in, and as a result those companies are still failing to produce competitive vehicles.
I do not think that it is certain that China supports more its key industries than USA, even if that is frequently claimed, but without any supporting numbers.
During the last few decades, I have almost never heard about a big US company making any big investment, like a new factory, or even just a new HQ, except after receiving very substantial state aids in the form of various kinds of tax reductions.
In many parts of Europe this kind of aid that is received in USA by most big companies would be labelled as illegal state aid and forbidden.
"what you see is 'protectionism' is to a lawmaker a way to ensure that the local company survives and provides jobs for the local region/state, etc."
This is laughable given the history of the auto industry in America.
Foreign automakers (Toyota, BMW, etc.) build competitive factories in southern states and often paid better wages and delivered higher quality products. All this without decades of protection.
U.S. auto jobs still got wrecked despite the decades of "By American" policies anyway, since domestic auto companies decided to automate and offshore much of the work.