I'll add a bit of nuance here: something that is underappreciated is that China does extremely good contact tracing.
Cities do not go into full-on lockdown over a single case. The first reaction is to rapidly do contact tracing, and to quarantine and PCR test all close contacts of the infected person. This is done within hours. The building or neighborhood in which the person lives might be locked down, and there will be testing in the neighborhood.
After doing this contract-tracing work, it sometimes becomes clear that there is a larger outbreak that has gone unnoticed. If the public health authorities think they can't control the outbreak with contact-tracing alone, that's when larger-scale lockdowns occur.
The recent outbreak in Baise is a good example of this: one person tested positive, but it became clear that they had been infected for a week or more, and that they had gone to all sorts of mass gatherings. That's why the city locked down.
On the other end of the scale, Shanghai had some Omicron cases recently, but they were extremely targeted in their response, like shutting down individual buildings. They were able to end the outbreak without shutting down the city.
It's amazing how good a totalitarian government can be at tracking and controlling the movement of their citizens. Don't get me wrong for the most part the average Chinese citizen gets a pretty good deal from the government. It's just scary how much power the government has and how little freedom the people could have should the government wish it.
Taiwan and South Korea also do a lot of cellphone tracking.
So does the NSA, but for completely different reasons...
> how little freedom the people could have should the government wish it.
In some ways, yes, but even the Chinese government is subject to pressure from public opinion. A major reason why the government continues the zero-CoVID policy is that it's popular. There are also scandals that force a change in policy: for example, changes to how the Xi'an lockdown was implemented after a number of highly publicized stories of individuals who suffered because of rigidly enforced rules.
Cities do not go into full-on lockdown over a single case. The first reaction is to rapidly do contact tracing, and to quarantine and PCR test all close contacts of the infected person. This is done within hours. The building or neighborhood in which the person lives might be locked down, and there will be testing in the neighborhood.
After doing this contract-tracing work, it sometimes becomes clear that there is a larger outbreak that has gone unnoticed. If the public health authorities think they can't control the outbreak with contact-tracing alone, that's when larger-scale lockdowns occur.
The recent outbreak in Baise is a good example of this: one person tested positive, but it became clear that they had been infected for a week or more, and that they had gone to all sorts of mass gatherings. That's why the city locked down.
On the other end of the scale, Shanghai had some Omicron cases recently, but they were extremely targeted in their response, like shutting down individual buildings. They were able to end the outbreak without shutting down the city.