Everyday Alan?
Do they quarantine the entire city for 2 weeks and let no one in or out, or do they test everyone that enters?
This is China (now - HK has pretty much lost its independence, such as it was). China, I'm sure, will test every one going in and track them too - if it wants to push HK to zero virus status like the rest of China. Worth noting that since China is free they do not need to test travellers from china to HK. I'm sure they are already testing everyone HK -> China.
Mass testing and tracking those tested reliably is the way to beat this virus. It requires efficient fast test capacity, and a willingness to interfere with your population's freedom just a bit more than most Western countries will countenance.
This virus has political repercussions which are unsettling and I think not yet fully understood. the bargain with government is that citizens give up some freedom in return for some benefits. The question is: how much?
I'm not saying this advocating an authoritarian government. I am asking which freedoms are worth what? We see the same question asked over internet freedom? I don't think anyone knows the answers yet.