Extreme governments tend to attract two types of people; the wolves and coyotes. Wolves genuinely believe in the ideology and participate because of that belief. Coyotes participate because it's better to be on the inside of an extreme regime than the outside, they are there for benefits or protection.
I sincerely doubt that the majority of people within the government in places like North Korea or China are actually such hardliners, but it's dangerous NOT to be. What tends to happen is the same thing that happens in politics everywhere; a few hardliners lead the charge and others follow because they'll follow anything that feeds them or protects them. You may be a politician in North Korea, but do you really want to stick your neck out to try to change the system when you are as liable to get sent to a labor camp?
There was a line from A Man For All Seasons when King Henry is talking to Thomas More, "There are those like Norfolk who follow me because I wear the crown, those like Master Cromwell who follow me because they are jackals with sharp teeth and I'm their tiger, there's a mass that follows me because it follows anything that moves."
So it goes with extreme regimes.