This is also in part due to tax revenue. Because of Prop 13, residential units in CA generate very little property tax revenue (revenue which doesn't grow much until the property changes hands, which is unpredictable). Commercial units don't have this problem, so municipalities can depend on a decent amount of property tax, with predictable increases over time.

Prop 13 applies to commercial property too, I'm pretty sure.

I think commercial property just doesn't burden the city. A Google office has private security, a fire suppression system, and doesn't house kids who need to attend the school district.

Commercial property does burden the transit systems (LOL for CA) and roads. The road issue is pernicious because they take up enormous amounts of real estate to begin with and are extremely difficult to expand after the fact. This is one of the primary arguments against building high-rise housing in SoCal. Neither the transit systems nor the roads are able to deal with the additional people. The roads probably never will at this point--there is no room to expand them. Yet the transit systems are woefully underdeveloped for the size of the population and would take years to catch up even if the local politics supported them.