I was with you until the "unlike San Francisco" about building. Unless you mean single family homes, San Francisco is seemingly permitting and building about the same per person as Santa Clara County (http://my.paragon-re.com/Docs/General/SixtyFortyImages/New-C... from http://www.paragon-re.com/San_Francisco_Housing_Development_...) while San Mateo is way underweight: with almost the same population as San Francisco, San Mateo county approved about half as many units. So while it's true that most of the new units are in SOMA, I think they still count ;).