It's not exactly all about supply and I talked about that in my original comment but maybe that needs clarification. Yes the prices are high because supply is limited, normally that would drive construction but because the prices are so extremely high and interest rates so low almost everyone has to buy housing with credit. One of the many problems with this is that lenders get to be picky about what exactly people are allowed to buy and one of the things they don't like is people financing new construction. The result is people who could otherwise afford to construct new housing (and construct it in more efficient ways) for themselves in less populated places being forced to compete for the already short supply.
It’s all about supply.