The real question is why can't we get much denser housing (e.g. condos) and a smaller commute.
At least for Seattle, it seems like the liability for the builder and the costs don't really justify building for less than some un-sellable amount (e.g. $1k / sqft) [0]
[0] https://www.reddit.com/r/SeattleWA/comments/wnkwvp/comment/i...