Comparing a roaming feline to roaming attack dogs
The obvious reason cats don't have the same restrictions is that they don't pose a danger to humans. Cat's don't run in packs to rile up other animals and people. They don't dig up stuff or knock over garbage cans in search of food. Some cats prefer indoors. For the others I don't know how you would contain them unless you fenced (with roof) the entire property.
I guess I'm mostly alone here in that I have zero issue with roaming cats. I wish we had more outdoor cats as they would help control the seasonal rodent population. Unfortunately we have another 4 legged critter, the Coyote, that keeps the cat population in check.
"Your cat's gotta s*&t sometime" Robin Williams.