It all depends on the City regulations. Most cities have different regs for apartments and condos. Carlsbad for instance requires additional parking, more recreation space, extra storage, etc for condo units. They associate a higher standard of living with the condo vs. the apartment. So when it comes time to convert, the builder would have to upgrade all the amenities, which is some cases isn’t possible (not enough room for parking, extra storage, etc.). By doing this Carlsbad has been able to prevent the mass conversions. As far as I know there have been only several small (handful of units) conversions in Carlsbad.
Other cities, including San Diego have much less restrictions on the conversions. A simple facelift and airspace subdivision and you’re done. This led to WAY too many conversions in San Diego. You might have read that recently San Diego has considered tightening their regulations and even had a lawsuit over whether an environmental review was necessary for the conversion.
