A lot of those conversions are illegal and substandard. It has been going on for decades. The various city fees for a 500 sq ft ADU, when I investigated it about a decade ago, ran well into 20-30% of the budget for the ADU.
You are preaching to the choir here. I loved when Micah Posner, one of the chief NIMBYs of Santa Cruz, turned out to be an illegal ADU slumlord. That in my opinion explains a lot about how Santa Cruz really works. Or as I refer to it to outsiders: Mayberry politics by the sea.
“Standard” is one of the reasons costs are so high. New builds and large remodels in my city require overhead sprinkler systems... why? 2 car garages too, even though everyone I know uses them for storage or as a workshop. We need to lower housing standards if we want to house everyone.