[zamfi]

Zoning also creates this "positive" (in the technical, not social sense) feedback loop, where housing is so expensive that it drives up the cost of any kind of local production, including housing, because labor is (now) the primary driver of construction costs in California.

That said, building codes also drive up housing construction costs: originally intended for safety, building codes now also enforce energy efficiency (including window size, insulation, etc.), accessibility, sound transmission, material selection (for reasons other than safety), beyond the usual structural design, electrical/HVAC safety, and fire concerns.

This is before we even get to planning codes (i.e., zoning) which has restrictions on lot coverage, etc. that end up causing stronger correlations between land prices and unit costs.