Competition is good! Unless it makes shareholders sad.
Slave labor is a system in which a person is bought sold and indentured to a master for a substantial duration, often life. Their labor is coerced as property of that master.
That is not how China produces cars. They use highly automated systems and paid workers like everywhere else. While Chinese workers are paid less due to the forces of unequal exchange (a system imposed by the US) and an export economy (a system usually imposed by the US but more of a 4D chess move by China to develop productive forces, with the US gladly taking the deal for exploitation), that is not really why the cars are so much cheaper. It is because China has highly concentrated industry and a much less financialized system.
Speaking about “fair” is amazing in this context. The US is simply trying to protect domestic monopsony industry and to damage Chinese industry. This is a jingoistic and corporate policy.
Chattel slavery is different than indentured servitude. There is no ownership of the indentured servant, but they are forced to work against their will. This is the slavery found in Xinjiang, as well as the US penal system.
They can’t form new trade unions because everyone already has to join a registered trade union.
what are you smoking https://www.reuters.com/world/china/how-unions-work-china-2021-09-02/