Yeah but that's the same fir any car manufacturer aynwhere. VW is extremely subsidized by Germany, US bailed out their bankrupt manufacturers after 2008, same with France, Japan, Korea. UK didn't do that, or stopped doing that, and their car industry collapsed. Even for countries doing only manufacturing for other nations brands it's so common to heavily subsidize those factories to be able to get local production jobs.
It is, on paper a private company
But you need to understand this is China. BYD is extremely heavily subsidized by the Chinese government. For example, this 2016 article https://www.forbes.com/sites/mclifford/2016/07/26/with-a-lit... mentions
> In the five years ending December 31, 2015, the company reported receiving a total of 2.9 billion yuan ($435 million) in government support.
and that's just the reported support, there are tricks the government can play with for example labor costs, transferring R&D and so forth.