You answered your own question. The simple law of supply and demand can create unlivable wages for one. By controlling supply, you decide what types of people c

You answered your own question. The simple law of supply and demand can create unlivable wages for one. By controlling supply, you decide what types of people can make a livable wage. Maybe you want locals with families to have the opportunity to drive. So you control the supply until they can afford local rents and still have time to spend with their kids. Of course, cities often turned it into extortion, but they don't have to do that.