I don't see how holding a person responsible for their dogs actions has anything to do with BSL. Regardless of what breed it is, if a dog does something that the owner could have prevented, then yes, the owner should 100% be held responsible. If I'm an idiot and I let my Lab get out and it attacks somebody, then I should pay for all medical costs and be fined with letting my dog get lose and with investigation, determine if the dog is dangerous. Doesn't matter the breed, the owner should be held responsible.