The housing market is overpriced by design by the capitalists, via the use of zoning laws and building codes. This is done so people are forced to work long hours, resulting in further productivity gains for the capitalists.

It's not rocket science to mass construct cheap, insulated granny flats, however it would obliterate the profits of the oligarchs, if people were only working half the hours they are currently, their profits would not only halve, it would shrink even more, since there would be insufficient manpower for some of their capitalistic endeavors.