Are you joking? In the UK they can offset rental income against their mortgage payments (EDIT: mortgage interest payments), meaning they only pay income tax on their "profit" while also benefitting from the capital appreciation. (Admittedly this is changing from 2017 [0])
This, coupled with low interest rates means that landlords will take out additional mortgages to buy new properties even if they could afford to pay cash.
Landlords have been able to act like mini hedge funds, making huge bets on the housing market using cheap borrowed money. Some will get badly burned when/if interest rates rise and property values fall, but that doesn't look like happening any time soon.
You pay income tax on the profit you made, but you can deduct property taxes, mortgage interest, maintenance expenses, and most importantly - you can deduct the entire value of your house (building, not land) over 27.5 years (at least in NJ). The idea behind that is that you will essentially need to rebuild your entire house after 27 years. However, since you can deduct maintenance costs along the way, you really don’t have to rebuild your entire house all at once, so it works out in the landlord’s favor.
The only down side to the last part is that if you ever decide to sell the property, you need to pay full income tax on the portion of the value of which you have deducted in previous years.
Either way, rental income is taxed fairly with respect to some other forms of business.
This, coupled with low interest rates means that landlords will take out additional mortgages to buy new properties even if they could afford to pay cash.
Landlords have been able to act like mini hedge funds, making huge bets on the housing market using cheap borrowed money. Some will get badly burned when/if interest rates rise and property values fall, but that doesn't look like happening any time soon.
[0] http://www.wrigleys.co.uk/news/property/budget-2015---tax-ch...