SF is flush right now, which makes it particularly outrageous that it doesn't invest in infrastructure. But SF's behavior also tells you how cities got so deeply in debt with nothing to show for it.
E.g. in Maryland, nothing precludes Baltimore from building its own broadband network. It just has no money. Ditto Chicago, or New York. The laws applying to Philadelphia or anywhere in California shouldn't really stop construction either.
The NIMBY is strong in San Francisco. Apparently, even the imposition of the above-ground junction boxes are too much for people here, and so, once again, "We are why we can't have nice things."
Even — if not especially — in a place like San Francisco.
My choices, where I live, are Comcast and DSL (I'm just out of LoS for Monkeybrains). So I give Sonic money every month for a pretty hideous dollar:bandwidth ratio, comparatively, because that's still better than Comcast, in my book.
So yes, I could choose to use AT&T, but I would be getting substantially worse service. All cities should be investing in building out infrastructure themselves, as it would increase the desire for companies and people to live and work where they have better connectivity.