There are some fairly simple unspoken rules (e.g., "don't talk shit about the government") that everyone knows, and if you follow them, nothing will ever happen to you. In other words, the Chinese government's oppression is consistent and systematic - a far cry from the secret police, death squads, random people nabbed off the street sort of perception that many Americans seem to have.

This has probably greatly helped the longevity of the current regime. People will rebel if they see no effective, guaranteed way to dodge your oppression, but most will fall in line if you can give them a more or less guaranteed way to stay out of trouble with minimum tangible sacrifice.