Sure, I don't really have a problem with landlords benefitting from investing into a house and renting it. I'm kind of with Adam Smith on the problems of rent-seeking of the value of the raw land, but I'm not sure a better system than private property can be found for dealing with that.

> The favelas in Latin America, whose property are they actually built on?

Maybe somebody elses, maybe nobody's, maybe their own? I have no idea. If you aren't discriminating you can build a house brick by brick anywhere until someone with guns or a sledgehammer makes you stop, be it a land owner, gangster, government, whoever. I'd be interested in knowing myself.