Unfortunately there are owners of such breeds who say their dog would never hurt anyone. These aggressive traits, bred in to them generations ago are inherent.
I have a French sheepdog, who, despite being blind, will set outside moving her head to work out where sounds, that I cannot hear, are coming from. I mentioned it to the vet once and he pointed out that it was bred into her ancestors who guarded sheep and stayed alert for the occasional marauding wolf. She also knows when thunderstorms are coming, sometimes an hour before they hit us.
I've had terriers who haven't had lone access to the countryside but who have found moles with great ease whilst out on walks. Bred into their ancestors.