This is equally the case in most other US cities, most especially the expensive ones, but even including the likes of Chicago. It's kind of baffling: a four bedroom house with one kitchen and four roommates is perfectly fine per the zoning code, but that same house split into two apartments with two people living in each one would only be allowed in a relatively small fraction of the city (generally a smaller fraction than _actually has_ such buildings, btw). It's almost like the zoning bureaucrats think stoves are some kind of evil that needs to be strictly limited.

They should get Japanese engineers to come in and build the apartment buildings then. Tokyo is still standing.

has nothing to do with that, has everything to do with maintaining the "look and feel" of SF.