(I'm an Architect who has built in SF)

Parking spaces, front yards, back yards, building heights, building types, density etc are all City Planning functions, and you're right, have little to do with life/safety typically, and in many ways are quite destructive by making walkable livable cities very difficult to do now.

The Building codes, on the other hand, have evolved with each disaster over the last century or two - a building collapsing in an earthquake, people dying in fires, etc. So those have real life/safety protection as a primary directive.

One San Francisco-specific building code that might make it difficult to subdivide an office building into smaller rooms is SFBC 1204 https://codelibrary.amlegal.com/codes/san_francisco/latest/s... that requires almost all habitable rooms to have a window for natural light. In San Francisco, we trust mechanical ventilation, but for some reason we don’t trust electric lights. I think this code is an obsolete holdover that has nothing to do with health or safety anymore.

>But building codes in many places in the USA disallow making places that small.

Given how little exercise people get and that we are typically glued to a screen (tv, laptop, or phone) during waking hours, I could see an argument for lowering floor space minimums.

Code minimum bedroom sizes are pretty small: https://buildingcodetrainer.com/minimum-bedroom-size/