Why would a developer build anything but the priciest luxury rentals? There is no economic incentive to build small places for small rents. There ain't no such thing as a free market for *renters*. Every advantage and price increase trick is on the side of the the property owners.
Developers will never, ever build enough units to drop rental prices. That would be stupid. They will build to keep supply high for the highest incomes, and let the lower price units dribble away into condos, which keeps rents high and induces more pricey condo contrstuction.
There is no incentive whatsoever to build cheap apartments. A decentive, really, because the neighbors will fight to the death anyone who tries to put low-income people in their Zillow Zone.