Hasn’t the US been equally so, including the auto company bailouts, government fleet purchases restricted to US-made vehicles, US national moves to secure supply chain inputs for the auto makers, etc.?

The main difference that I see isn’t protectionism, it’s that BYD took a direction the market wanted, whereas US auto makers have not produced vehicles that were appealing to consumers who had choices.

BYD's direction was largely at the behest of the Chinese government, who were willing to demand things of BYD in exchange for that protectionism, instead of wringing their hands and saying "nothing you can do about the market" while simultaneously propping up industries of national strategic significance.