> Have high vacancy taxes, with an actual inspection and enforcement mechanism.
...only such taxes will bite landlords every time they have a legitimate vacancy between tenants.
> Structure taxes associated with the sale of a property be inversely proportional to the time time since the last sale.
... Only now people cannot afford to sell a recently purchased home to care for an unexpectedly ill relative in another state. Or take a new job opportunity. Or afford to move to follow their heart. Etc.
> Create a space for not-for-profit housing foundations, land trusts, etc.
...only now the trusts are competing with landlords with entirely different tax structures and perverse incentives to create bureaucratic nonsense because they don't compete in the fully free market.
> Build nice public housing for the middle class, without stigma.
...only now no one wants to build this because they're taxed when the new properties are vacant per your earlier proposal. And now the public is likely on the hook for losses.
> Label every house with data about what they pay in property tax, how much of a benefit they get from things like the mortgage interest deduction, and what any rental property is charging their tenants.
...only now people's financial privacy is wildly violated.
> Teach children to shame rent-seeking behavior instead of shaming people for their bodies.
... Only now, really? Really? Like in the schools we should teach people that providing a way for others to have a roof over their heads at considerable business risk is shameful? The ones that are presently being paid zero rent without recourse due to local edicts?
> Give tenants a small deduction on their rent.
... Only now you're trusting people to not inflate their reported rent to gain illicit tax breaks.
Any other unintended consequences worth spit balling?