I would think the difference between a tax and a rent is that taxes only apply to the same piece of property once and rent applies over and over. If I'm paid a hundred thousand dollars I pay income tax on that once and after that I can keep it in a trunk until the end of time without anyone worrying about it. Whereas if I spend a hundred thousand dollars on a parcel of land the only thing stopping me from paying an infinite amount of "rent" (taxes) on it is the fact one day I'll drop dead and then someone else will start paying the infinite amount of rent on it. That property tax on a square foot of grass totals much less than rent on a square foot of apartment seems like a difference only in amount, not in fundamental nature.