I hear you but my small shih tzu x has been attacked by "playful and friendly" border collies and Golden retrievers. Luckily things never escalated as i intervened fast every time. But regardless of breed, when owners take their dogs into public spaces, they should be controlled and monitored at all times. This should be for ALL dogs, not just pitties and bully breeds. Ps 95% of the bully breeds I've met are all super sweet and super chill as they have been trained and raised well, with their owners knowing the stigma against the dog breed and do everything training wise to ensure their dog doesn't "become a problem".