As a dog owner, you may find leash laws to be anything from unnecessary to unreasonable, especially if you have the sweetest dog to roam the face of the planet. You may think the only reason a dog should be restrained is if it is aggressive, inclined to attack people or other dogs. You therefore may feel entirely baffled why someone would get their panties up in a bunch to see your dog bounding happily across a park, especially when it looks so darned cute doing so.
As someone who needs to stay away from dogs, for reasons that are invisible to the outside observer, I'd like to share some considerations for keeping your dog on a leash, not because it's the law, but because you care about the wellbeing of your fellow humans:
First, some people are afraid of dogs, for a host of reasons, including past trauma. I know of people who were bitten by dogs, as the owners shouted from across the park, "Don't worry, he's friendly!" Of course he's friendly to you. He's your dog. Relationships, and therefore interactions, are contextual. Just as a child might be the loveliest little munchkin ever, to her parents, but a terror to other children on the school playground, so can a dog have an entirely different interaction with the person who feeds him and with a random stranger he encounters.
Second, some people are allergic to dogs, in some cases severely so. Getting a dog's nose or hair on one's clothing can lead to an asthmatic reaction. In case you don't know how crummy that is, hold your breath until your face turns purple, and you'll start to get the gist. This situation is complicated by the logistics of getting into one's car or walking into one's house with clothing contaminated by dog hairs. It's not like you can strip naked before going home. (We have laws about that too).
Third, some people have disabilities - both visible and invisible - that make it dangerous for the fast, abrupt, and unpredictable movement of dogs, particularly on a narrow trail, even if the dogs don't actually make contact. In my own case, after a decade of chronic and debilitating pain - through which I was alternately bedridden, housebound, and wheelchair bound - my body is hypersensitive. So when a dog comes flying at me, my body braces itself, all my nerves fire off, and all my micro-muscles contract - triggering a pain episode that can last for hours, days, or weeks.
On a number of occasions, I enjoyed a perfectly lovely walk or jog, until a dog came barreling at me - following which I hobbled my way back to the car, in pain. That knowledge of how things can go down, in and of itself, exacerbates the fight-or-flight stress response my body goes through, every time an unleashed dog is in my vicinity.
Then there are people who simply don't appreciate being startled by dogs, others who altogether dislike dogs, and still others whose own dogs - especially the teeny-tiny, quivering types - need protection from strange pooches.
The bottom line is that there are many people who need dogs under control in shared space, for health, safety, and/or comfort reasons. I believe it is for these reasons, as well as for reasons related to order, cleanliness, and ecology, that there are leash laws. This reality is no way a commentary or judgment on dogs as a species. We can love and adore dogs in general, and/or love our own family dogs in particular, but not enjoy or feel safe with strange dogs running all over the damn place.
Consider it this way: Dogs sans leashes is kind of smoking circa 1980s.
Prior to the no-smoking laws throughout the United States, those with asthma, chemical sensitivity, and allergies were de facto barred from restaurants, bars, nightclubs, and even airplanes. "It's the job of smoke to travel," a smoker I interviewed for an article remarked many years ago, indicating that where there was a lit cigarette, everyone in the vicinity was affected, regardless of designated smoking/non-smoking sections.
Similarly, where there is a dog off-leash, everyone in the vicinity is impacted - not only by a dog actually charging at us, but by the possibility that it might. To avoid the consequences that may follow, and the anxiety of the dealing with the situation entirely, numerous people have stopped going to city parks and trails or, alternately still go but walk along the sidelines, on guard and on edge.
In my own case, when I see your dog running around off-leash, I go to a different part of the park, or I leave the park altogether. You may not realize you are affecting me, because - having to stay away from dogs-on-the-loose - I cannot get close enough to you to ask you to please put a leash on your dog. Besides, half the time, I have noticed that you are not even carrying a leash.
As an alternative to outright defying leash laws, dog owners can take a beloved pooch to any number of dog parks, designed for those who want to set their own dogs free or who want to personally enjoy the exuberance of other people's dogs. Perhaps there are not enough dog parks in your city - a perfectly valid critique. In that case, there is the option of petitioning a city for more such parks. While that action may be a royal pain in the ass, the alternative of your dog-liberating, law-defying rebellion is this:
When your dog is free, I am not.