I just spent two weeks in Germany and noticed that almost nobody there keeps their dog on a leash. Dogs are loose on city streets, in open parks, pretty much everywhere. No one seemed to have an issue with it, and none of the dogs were misbehaving -- all of them were keeping up with their owners and not disturbing anyone else.

Maybe this is a cultural thing, both in terms of people's expectations of encountering dogs in public places, and in terms of the way dogs are trained and conditioned to respond to stimuli. Maybe keeping dogs on leashes prevents them from learning the skills they need to be off-leash reliably.