&lt;The Bay Area has been really bad about building&gt;<p>This is largely due to politics.  If you were a speculator considering building a rental apartment building, you face:<p>1) Rent control.  (Those cities and counties that don&#x27;t have it are all considering it.)<p>2) <i>Requirements that you allocate a percentage of your units as limited to &quot;low income housing&quot;</i>, with those units becoming permanently constrained<p>3) permit costs, neighborhood opposition, and other city-specific barriers<p>4) high material prices and construction costs (e.g. earthquake and flood codes)<p>5) high labor costs