Rental income is considered income, and taxed assuming reasonable tax brackets much higher than investment income (That is to say, caiptal-gains. Interest/Dividends are also taxed at the higher income rate)

The cost of maintaining a livable home, property taxes, insurance, property depreciation, and renter interactions eat into the supposed windfall that landlords make.

I’m not saying it doesn’t suck sometimes and that certainly these formulas are out of whack in some situations, but there are no easy answers.