Earlier quoted context omitted.
How would that be done? If an address wasn’t claimed for a personal tax return for an owner or tenant, it gets a big tax bill?
This would be specifically to fix the problem of a builder making a bunch of apartments and slowly letting them into the market to artificially inflate home values. Presumably, the building company would be the owners for all the empty apartments which would make it easy to find and tax. It would be more difficult to detect someone buying a home/apartment as an "investment".
That isn't the reason rent is high in SF.