I feel like it's a thing where pitbulls have a tendency to be more aggressive (same as terriers) but can do more harm. That said, that tendency isn't something that can't be overcome by training. Essentially I think more commonly aggressive breeds, like pitbulls and terriers should require some amount of training to be kept. That way there's just less conflict, and if anyone complains it's just telling on themselves that they were never going to train it anyway.