We hold kid's hands while they cross the street so they don't go willy-nilly running around in it. Dogs don't get any smarter than a 3 year old child at best. So unless you're in favor of letting 2 year olds run around with no restraint whatsoever, it's a bad analogy.
I'm glad we have leash laws in my city that most people in my neighborhood follow. There are only two loose dogs that I see with any regularity and both are small and seem to have enough sense to stay far away from me and my dogs. One I know is let out in an unfenced front yard with no supervision (keep in mind, I live in a city, front yards are small and the road is
right there), the other I think is more a case of people with an unsecured fence who can't be bothered to fix it. I think the people with the tiiiiny yorkie and the fence with huge, gaping holes moved away. That dog
did manage to find its way in to my securely fenced back yard one day (my yard is securely fenced for 55-100 lb. dogs, not 3 lb flullballs that can fit through cracks!).
OMG I'm so overprotective my dogs have no life they're so miserable they live in a sterile box!!!!