If we have that attitude to people owning things, then the first thing should be wealth tax on jewelry, cars, boats, and other luxury items which if you can't afford to pay the tax then you should be forced to sell it. I remember how popular that concept where here in EU when refugees had their jewelry taken by the government in order to pay for expenses and basic living. People have this weird attachment to objects that defy rational thought.
I get the sentiment, but in term of winning popular support it has some distinct emotional drawbacks.
If we want to specifically address vacant lots within city boundaries, a tax on that seems fair. Not many low income home owners live in their property owned vacant lots located inside city boundaries.