Right. But then you've changed the default from "not having to pay tax" to "having to pay tax". That is, far more people live in the house they own than rent out the one house they own and live somewhere else. Right now the 5% (say) who rent out the house they own get taxed, the 95% who live in the house they own don't. The change you propose would result in the 95% now also being taxed. That's fair, I suppose, but it's also the most drastic change you could make to create fairness. You could, for example, offer the 5% that the rent they pay could offset their rental income for tax purposes.

So why change it in the direction you propose? We're back at my initial complaint: This turns into "Saving money rather than spending it deprives us of the tax we would have received, so we'll tax your saving as if you had spent it. Don't own a cell phone? Pay us the taxes that would have been on your monthly bill anyway. Don't own a car? Pay us the registration fee anyway. Walk to work? Pay us the gasoline tax anyway. Don't drink alcohol? Pay us the taxes as if you did. Don't smoke? Pay us the taxes on the cigarettes that you could have smoked. Don't visit national parks? Pay us the entry fees anyway."

Do you see that that's insane? But if it's insane, why isn't "imputed rent" as something taxable insane?