California has been under-building housing for decades, to the extent that people will call this current activity a housing “boom” even though it’s only slightly above historic lows.
https://www.foxbusiness.com/economy/little-rock-homeless-pic...
California housing isn't "inefficient." The housing codes are made with the idea of keeping houses up through natural disasters and serviceable for a long time. We might modify that last provision (as Tokyo does, for example) but it comes with it's own problems.
The idea that somehow housing regulation increasing costs is the core or even a major contributor to the problem is one that requires substantial evidence.
Unless you're referring to "Californian contractors are overpaid," which seems more like a reflection of the expensive cost of living here than "inefficiency."
There is no denying that California refuses to build housing. This does raise the cost of Californian housing. However, this is characterized distinctly from efficiency of the housing regulations and building codes in most conversations specifically to avoid the dodge many developers present, "Housing codes are too strict, it's inefficient to build homes in California."
If I ended up misreading your post as a result of context, I apologize for doing so. I did not mean to put words into your mouth. But please consider that many other people may read this and read the same intent because of specific phrasing you're using.