==At significantly higher cost.==

Significantly higher building costs, but lower land acquisition costs.

Excerpt from a BuildZoom analysis:

"The high cost of housing in expensive coastal metros is not driven by construction costs. It is driven by the high cost of land which, in turn, reflects a scarcity of zoned units, not a scarcity of land per se."

https://www.buildzoom.com/blog/paying-for-dirt-where-have-ho...

==That the difference is in part due to policy doesn’t change that there is less availability==

Except the current policy explicitly limits the availability, they are one in the same.