We started putting armed police in schools to defend against school shootings. Not to intimidate students. The school officers here are generally older cops working part time with not much time left before retirement.

There still is a fundamental difference in the way that power is broken up in the US between states and federal and between different courts that are widely independent. You have a lot of levers to defend yourself if a state wants to initiate legal action against you. In China, you don't fight the CCP and win, ever. People often sue and win against the Federal Government.

There are many fundamental differences. We have rights to free speech, guns, due process, and hundreds of years of common law precedence to fall back on, in addition to a generally far more rebellious culture.

EDIT (reply to caraso): A lot, because if the surveillance is used against you, you have many levers of unaffiliated and totally separate branches of government to pull to come to your defense.