For the same reason that a city has a dog bylaw, a city needs a cat bylaw.
It is, once again, about respect for your neighbour. I may enjoy and even love my cat but other people may not share my view. Therefore, out of respect for my neighbours, I do not allow my cat to roam the neighbourhood. If all animal owners understood and practiced this attitude, a city would need no animal bylaws.
Trumping Trudeau: How Donald Trump will change Canada even if Justin Trudeau doesn't know it yet