Not sure about San Francisco, but if you put "garbage monopoly" into Google you get some real-life cases. One of the first hits is from Washington State where 2008 the Supreme Court held that the garbage monopoly is constitutional because trash collection is a public function (like police and fire departments) which just so happens to be outsourced to a private company.

I do know that, here in New Jersey, as far as I can tell, trash on the curb, which used to be owned by no one, is now owned by the state or maybe local government. This change has been happening all over this great land of ours to prevent people from taking the recyclables and recycling them for money elsewhere -- because the state (or local) government wants that money for itself. Also, there's a problem with identity theft and whatnot.

I looked into this because I was banned from my local electronics recycling when I tried to take computer parts away with me. Electronics recycling is collected by a private company -- if by "collected" you mean there's a drop-off point conveniently rarely open off in the swamp next to the sewage processing plant -- and the spokesman for that private company told me I was stealing when I took computer parts. I argued the point and eventually he also claimed that any hard drives might contain personal information and so it was a privacy issue.

The company has since forgotten I was banned and I can drop stuff off again, but I'm afraid to try and take anything. Also, my wife is tired of old computer parts cluttering up the place.