That's not what GP is claiming. He's claiming that a land tax would not be passed on to renters if instituted, because rent is being driven demand-side (what r

That's not what GP is claiming. He's claiming that a land tax would not be passed on to renters if instituted, because rent is being driven demand-side (what renters are willing to pay) not supply-side (cost to provide a house to people). Any attempt to increase rent would result in a lower demand by renters, meaning the market would fail to clear -- the rent would then need to be re-lowered. But you are correct, that rent shouldn't be higher than purchase plus upkeep. In the event of a land tax, rent holds constant but upkeep increases (taxes); consequently, for the equation to hold, purchases prices (and thus land values) will fall. And that's why this is so politically impossible to pass, even though it is considered the "least bad" tax economically. Land owners would see their assets sufficiently fall in value if a land tax were enacted.