You're confusing real estate with dwellings. Renting land is an issue for farmers. Adam Smith had a lot more sympathy for sharecroppers than for apartment dwellers. Even the most basic apartment represents tens of thousands of dollars in investment. No one is going to make that investment without hope of charging "rent". Modern standards don't allow for hovels to be built of local materials on vacant land in a few weeks, as was possible in Smith's time.