Because the last tenant put holes in the walls, their dog's piss caused the floor to lift, and the shower they plugged then overflowed fucked up the bathroom?
So there are repairs to do in order to make the place livable and then time to find somebody else who won't just wreck the place again?
Yeah there are lots of shit landlords but one of the continuing factors is the remaining good ones with a basement suite etc bailed after terrible tenants.
A vacancy tax is a good idea but there needs to be caveats for timelines especially if stuff like reasonable maintenance/repairs is taken into consideration.
Ironically my friends who bitched about "shit landlords" also happened to be the drinkin' smokin' big-dog-ownin' types who were the worst type of tenants and ruined shit for everyone else