One can then own land without actually doing anything with it - you can let it out at rates for others to use. You can't just let a car factory sit. And if you just own the building and land, and do nothing else, then yes- you're just charging rents. But generally owners have to work to own a factory, if at nothing else than making operation policy decisions.

Perhaps a trip thru "Poverty and Progress" is in order? George is better at this than I am.