The cultural differences wouldn't display by leaving of your friend :) there's so much more than "obedience".
They do not riot, because they, too, understand, that the capacity of hospitals is quite low comparable to the density of people.
The other points:
You can't just leave the country without being a foreigner. Chinese people need a Visa for the countries they want to enter.
The social score / if you participate in riots, you for sure will get identified.
The fear being hurt.
No other possibility, because the Chinese officials are really hard in that terms and they don't care if one get hurt.
No other possibility, because the doors are locked by the officials. No one can go to riot.
They use an app to track one's location and track whether one's in "red area". If so, you lose. Everyone have this app. Without app you can't even buy things on the market.
And of course, the CCP. They have a high membership rate. You can't do some jobs like teacher/professor without being a CCP member. So, they're full on the line of party, because they really believe in that. My exgirlfriend entered the party on her 18th, because her father was a doctor at a military hospital.
Being a non member gives you some disadvantages in some parts of live (indirectly, but there are some).
So, you have to speak the language (me do) and have to have lived there for a while (me did) to understand why they're doing it and why they're is not much withstanding of the people.
One of my girlfriends (haha) just arrived two weeks ago in europe. She says it's crazy over there. No end of the 0-covid in sight... Her flight was cancelled 8h before flight because of lockdown of the airport. She had to rebuy the tickets, go to Shanghai and start off there.. But she does not criticize or get angry when talking about this. Her family is still there. She is just happy to be in Europe, because of me and main purpose studying - not because of the measures.
But, yes. It's crazy.