It definitely IS state law, unless I'm not interpreting this correctly.

https://www.jdsupra.com/legalnews/new-california-compost-law...

It's probably just San Francisco. I have heard of something like that at the municipal level. I don't remember something like that when I visited family in Sacramento a couple months ago.

Seattle has something like that too, when I lived there seven years ago. We were provided bins for composting, and compost bins were in every resturant I went to.