Isn't all money "after tax" though? It all goes around. The exception would maybe be the treasury minting loans.

Everything is unfair. The housing crisis is unfair. Young families struggling to afford a family home is unfair. Having to pay into a pension system you'll never get to use is unfair. Land and housing is different from personal property. There's only so much to go around and we'll have to share. A property tax is one tool to incentivize efficient allocation, and to drive prices down.