Vacant home doesn't mean a house with no owner. I am not sure how getting divorced makes vacant home occupied.

if someone shows up there 3-4 days a week, how would you know? Even China doesn't have the surveillance setup to tell if someone is living in a house or not (well, they can check to see if it is renovated, and can check to see if the lights turn on at night). It isn't really a rule of law society, so you can't use "the trust but sometimes verify system" they used in Vancouver, and it is definitely not like Switzerland where your neighbors are constantly spying on you. It is a bit counter intuitive, but checking on these things is harder in China than in the west.

> if someone shows up there 3-4 days a week, how would you know?

Its the same thing as taxes. No one is stopping you from making up fake receipts. But you don't do that because its fraud.

Vacancy is hard to prove and typically proxies like water usage or having lights on are used, but they're inaccurate.