This whole dogs are animals/wolves and are unpredictable is just BS. While I hate to break it to you, but there are some breeds that are more prone to aggressive behavior than others, doesn't mean that with proper training a Pit, Dobber, or German Shepard can be loving and docile dogs and that breeds seen as not dangerous can still maul the fuck out of someone. Heres the thing though, there is a huge difference between the instinct of a wolf and a dog. For starters a Dog's genetic evolution has adapted them to be used to humans, this is why wild dogs, dogs that are not around humans, still attack when they come into contact with a human, they aren't afraid. A wolf on the other hand, is extremely timid and will flee first and only attack when its fearing for its life and feels it has no other choice. So polar opposite, where dogs will attack offensively, wolves only do so for hunting and defensive.
A dog that attacks any human is a dog that hasn't been taught that all humans are above them in the hierarchy, they have to be taught that among human, they (the dog) are the omega, when you have that taught, if they are being hurt (like a toddler would do) by another human, they will flee first and will snap back in aggression only if they can't get away which is a good thing because if they can't get away it means they are being attacked by someone and not being poked by a toddler, and anyone who wants to hurt a dog just for the sake of it, deserves everything that dog gives them. If a dog attacks randomly or shows any aggression towards humans was not trained correctly and you cannot blame the dog, it is the owner that is to blame.
I totally understand putting a dog that has attacked down, but really, if we put dogs down for that, humans should serve the same fate. I don't understand why a dog who attacks someone (and lives) is put down but a human that kills innocent people serves maybe 20 years in jail. And obviously the circumstances in which a dog attacks needs to be looked at because there are situations where someone had a dog that attacked a an intruder and saved the owners life by attacking the said intruder and the dog is put down, or when you have animal abusers who inflict pain upon and animal and when the dog gets the opportunity to attack back, the doge is put down as the result of the attack. Its just bullshit, when if a dog attacks for whatever reason, its put down but humans are perfectly capable of kidnap, rape and murder and get out of jail in only a few years.