What is the public good here? I'd imagine: having shops, instead of vacant properties. And extending to residential: having more housing supply. So we want to

What is the public good here? I'd imagine: having shops, instead of vacant properties. And extending to residential: having more housing supply. So we want to (1) incentivize landlords to put their property to use, instead of letting it lay vacant & (2) avoid making property owning so risky that no one wants to do it. It seems like a non-use tax + national economic hardship exception takes care of that nicely. Taxes on your limited-supply property (e.g. city cores) increase at 30/60/90/180/360 days of vacancy. Where vacancy is defined on average across a timespan (to prevent resetting timers with faux leases). And then coupled to an external index (e.g. national occupancy rates for property type) that decreases the increased tax if there's a deteriorating economic period. We want it to be financially painful to not have a tenant in your property. To the extent that landlords are incentivized to go to the trouble to offer their property to the public for use.