This is kind of part of the problem. Housing developers are enabling large hub cities to offload the cost of housing to smaller outlying towns. Of course, the developers aren't doing this willingly.
The other problem is that housing developers in California have a tendency to build huge, sprawling suburban communities. This just increases sprawl.
Imagine a 1 sq. mile tract of land. Assuming a housing developer builds a ton of two story, single family homes here, each on a 1/4 acre of land, we can calculate that they can build 2560 homes +/- 500 based on topography and landscaping etc. There are no reliable numbers as to the average of units in an apartment building. Therefore, we will have to make some assumptions. Let's go ahead and say that that the developer decides to build apartments instead of tract-homes. Each apartment building will be 2 acres in area. Even if the apartments are huge: 1500 sq ft +, we can calculate that a 2 acre apartment building can have about 20 units per floor. Lets say that these apartment buildings are a modest 2 stories tall. 20 * 2 = 40. That means, covering the same 1 sq. mile of land with modest apartment buildings could create 12800 residences. That's a 500% increase in residences.
In urban centers, zoning laws allow for much taller structures. Structures can be hybridized to allow for both commercial and residential tenants.
Building large, hybrid-use, multi-tenant structures will alleviate some of the pressure on the housing market and lead to shorter commutes for most people. This is because you can fit more people into a smaller land area. It's common sense I'm sure. So, why aren't developers building these structures? The short answer is that they can't. City zoning laws, angry property owners, and the lack of open land in desirable areas all get in the way.