I interviewed the "Chief Dogcatcher" (or City Veterinarian), Mr. Suraphong Wongsutthawart, in 2016, and then again in 2018.
I referred to other tourist places in Thailand, where they seem to be attacking this problem more forcefully. I asked him if the authorities could not do anything about the problem, how about hiring private firms? He advised against that.
He told me that people who start feeding dogs are legally considered their owners and are responsible for taking care of the dogs.
Strangely, when I called the office last week, based on a problem in my soi, some veterinarian told me that this is not the case. I guess I'll have to follow up on that...
Reading material (for Scandinavians... or users of Google Translate):
https://www.thailandstidende.com/component/k2/item/2870-si-fra-om-loshundene
https://www.thailandstidende.com/component/k2/item/3625-stadig-flere-loshunder-i-byen