Quarantine method has been stepped up, as people have been bailing on their quarantines. They used to do phone calls to confirm location ("are you where you're supposed to be?" "yup, I promise

")
But now you have to use tracking software (I think Whatsapp or Wechat) or wear an ankle bracelet.
I will say that all of Hong Kong should be thanking the protesters for killing the tourism industry before this virus broke out. If the tourism wasn't severely depressed going into this year's CNY travel, we would have been soooooooooo fucked.
This year, before any border controls, Lo Wu would saw around 78K travelers (including HK and non HK residents, and this includes both directions). SZ Bay: 43K Lok Ma Chau: 36K
Last year these numbers were
242K, 141K and 132K
So before any border controls, we were at 150K from 515K, and are now at 3K daily travelers. I wish I could find the numbers for mainland visitors only, I bet it's even more significant.
Either way, protesters are saving HK in more than a few ways.