I don’t think it’s as simple or straightforward as you make it out to be.
Suppose I have a 9 year old guard dog with signs posted: Keep Out and Beware of Dog. The dog is trained and has never left the yard. He’s only hurt one person. A few years ago he bit a small child who unwittingly pushed him and grabbed his food bowl while he was eating. The child recovered OK and, since this was the only bad incident, we didn’t euthanize the dog.
Now suppose some young men, perhaps drunk, stand outside my fence, in the dark, with a slingshot. They begin taunting the dog and pelting him with rocks. Some hit the dog, some hit the house. The dog becomes more and more agitated, snarling viciously at them through the fence. But they take no heed and continue yelling and pelting him.
So. If the dog jumps the fence and attacks them, who is at fault? Obviously, I would second guess my decision not to put the dog away earlier. But, really, what kind of idiot slings rocks at a viciously provoked animal? I would blame them more than myself.
Zoo officials are given one primary responsibility... keep animals and people separated so no one gets hurt.
They failed miserably.
If an agitated prisoner could escape this easily and go on a killing spree, we would be outraged.
THE HANDLER made the mistake. Not the Tiger. Did you miss that part?
If your dog breaks its chain and attacks and kills a neighborhood boy, who may or may not have been taunting it, you would be held responsible.
You may claim a defense of: “This chain is strong enough as long as nobody makes him mad.”
But you would lose your case.