To add some clarity for those of us not so au fait with the terminology, rent-seeking refers to economic rent, which here is the different in the apartment rent

To add some clarity for those of us not so au fait with the terminology, rent-seeking refers to economic rent, which here is the different in the apartment rental price actually charged (with the benefit of RealPage) and the price that would otherwise arise in a market which was free of collusion. The argument is that free markets are (somewhat) efficient and mean that we use our finite resources (like land) in the manner which generates the greatest economic benefit. Normally if you rent-seek by trying to jack up a price above what the market would dictate, someone will come along and out-compete you. The trouble is that it's difficult or impossible for someone to to produce a substitute good here, if there's no empty lot on the street and all the prices are artificially high then how can I come along and compete on price offering apartments on the same street?