Years ago wandering through a French town I got a sniff of something and looked around, to see a railed-off area with a sandpit, in which was deposited a couple of dog poos. I asked what it was, and was told that it was a dog toilet - normally people would pick up the poos, but because it was used regularly, passing dogs' stomachs were stimulated by the smell, and they went in to do their business.
Thought it was the most brilliant idea I'd ever seen. I don't know why every city or town doesn't do this.
My own dog tends to use only one place in the back garden to deposit his poo - a sheepdog, as close to the wild as a dog can get, and a very civilised little love who's always eager to please his humans.