Are they well stocked, too? We've got plenty of those around Paris, especially close to parks and green squares. They often look empty. And in any case, people don't seem to have their own bags either.
I don't have hard numbers, but it's generally a good idea to look where you step on the sidewalks. Although it's true that subjectively it seems somewhat better than a 5-10 years ago.
maybe the humans are parasites on the dogs, although seeing the humans throw out the poop later would certainly complicate the graph of life the aliens were developing for our planet.
https://www.robi-ag.ch
(I am disappointed they changed the logo. The old one was:
https://grundig9000.com/storm/robidog.jpg )