If that is the case why are they allowed to own a pet or have a kid?

The psychology of abusers of any kind is well beyond my understanding. Far as the "why are they allowed, obviously it’s they haven’t been caught or enforcement didn’t do their job right. Laws are weak, enforcement is selective… and unfortunately the people who do enforce, have a tendency to be the kind of people that are more likely to sympethise with finding enjoyment of exerting control of people or animals that are not in a position to fight back.