Why? Because apparently they need some more incentive to keep units occupied. Also, even though a property might be vacant, there’s still imputed rental income there. Its owner is just receiving it in the form of enjoying the unit for himself instead of receiving an actual rent check from a tenant. That imputed rent ought to be taxed like any other income.
No, you’re wrong. Income is any money that someone brings in.
Wages, salary, or “earned income” are the terms used to signify that it was money paid for labor.
Rent from properties is income.