China has an economic leverage that allows it to change not just vies that play in its borders, but movies that play outside it as well. If hollywood studios make a movie that it doesn't like, for any number of reasons, they will perhaps not let their next five movies in. There are some easy rules, like no masturbation. But then there are other more thematic rules like no negative outlooks on life, no portrayals of suicide. It's fine if there's government corruption in other countries on screens.