>>507515751California is in a dry earthquake zone.
In the 1990s developers figured out the cheapest way to make high square footage homes on a tiny plot to maximize selling price and capitalize on the real estate jump in price brought on by importing most illegals and legal immigrants to the entire nation to that state.
They then took that building method nationwide, even to places it is unsuitable.
Masonry structures in earthquakes are more prone to burying the inhabitants in heavy rubble. California is a high earthquake zone.