It's kinda easy to make it look like a building is occupied and avoid the fine. It's kinda hard for authorities to prove otherwise.
It's hard to off-shore property in a tax haven too.
It's one of those policies that is popular with virtually everyone right until the moment they get into power and meet the wealthy landowners/donors.
At some point, the effort required to cover up the lack of occupancy is equivalent to renting out the place.
Utility bills for example. Is the electricity utilization random enough or a little too constant? What about water? Natural gas? Pay the garbage collectors to rat out homes that never leave anything out.
Are the windows always left open even on the hottest days and no A/C?
Is the keyfob for entry never used?
Ultimately, every tax can be evaded. Income, sales, corporate. This one won’t be any different.
I do wonder who might rat out their completely quiet neighbour though.
The real tell will be the every 5 minute reports that smart meters can generate on usage: much harder to fake with timers.