The right generally takes as a given that the cause of the problem (if there is a problem at all) is that there is not enough housing and we just have to build more.
The left argues that in we in fact do have enough units that could be used for housing (or at least the situation is not as clear-cut), but that other factors prevent them to be available at affordable prices, like the effects of extreme income and wealth inequality on the market.
Personally, I think the "left-wing" explanation makes more sense - at least I've never understood where that sudden shortage of physical housing is supposed to have come from. We neither had a population explosion, nor a war or catastrophe that would have destroyed a lot of houses. So then why would there have been "enough" housing in the past but not anymore today?