[zamfi]

> The $/sqft of housing tends to go up as density increases

This is only true generally, not within a specific neighborhood, and it's because of correlations between demand and density.

If you look at a neighborhood with mixed SFH and condos, the condo $/sqft is lower than the SFH $/sqft. (To be clear: that's $/sqft of housing space not of land).

Having a diversity of density enables home pricing at different points. Looking only at SFH (as this article does) is missing the forest for the trees, IMO.