Montevideo is a pretty big city having a population of over 1.3 million people and many of those people have dogs. Here you will not likely see dog poo on the sidewalks or streets. We have not seen dogs roaming free, all are on leashes and someone is walking them. And we have seen the people around our apartment using baggies to clean up after their pets.
While walking on one of the side streets just a block or so from our apartment, I saw an empty large gallon water container tied to a tree. I could not figure out what the purpose was until on another walk further away I spotted this.
Yes, you got it. Someone filled this empty jug with supermarket bags. Just the right size to pick up your pets poo. For a large city, it is pretty well maintained and I was happy to see the pro-active folks trying to keep their city clean.
Finding our Paradise in South America 
That is wonderful. They really love their city.