I think property taxes should be part land value and part land use, with no explicit tax on buildings. That lets the local government unbalance tax rates to be even more in favor of dense apartment and industrial space over parking lots, or whatever their priorities are.
The goal is putting vacant lots in so much tax debt that they go underwater. After that the city can seize them, pay off the other creditors and put the land to better use as housing projects, a community center or low rent small business space. Leaving everything to markets is a big mistake.
No, the goal is to facilitate optimal use of land. The fact that parking lots are inefficient is a coincidence and you will likely find that your "community center" is equally useless. By "unbalancing" this and that and whatever you personally prefer for ideological reasons, you are undermining the whole system.
The goal is putting vacant lots in so much tax debt that they go underwater. After that the city can seize them, pay off the other creditors and put the land to better use as housing projects, a community center or low rent small business space. Leaving everything to markets is a big mistake.