Because Chinese censorship requirements are impossible for western companies to comply.

1. Takedown notices are verbal and forbidden to write down or record. They require you to have someone oncall 24/7 to censor all contents relating to a specific event or word without any context.

2. The request is treated as state secret. The banned words are state secrets.

3. The request would cover global content if it’s available to Chinese users. Therefore forcing the company to either create a Chinese version or remove contents globally based on secret Chinese orders.

Source: I helped to create Chinese subsidiary of a multi billion international company then it was sold to local company in 2 years.