have a little fuzzy wuzzy kitty cat. My fuzzy wuzzy kitty cat has sharp claws and sharp teeth. These instruments of death, however, are relatively small and only result in small scratches when me and my fuzzy wuzzy kitty cat "play" fight. When you have a 600 pound white tiger, or a slightly smaller regular tiger, and they decide to "play" fight, you are in the shizzy.
I agree...that's it in a nutshell. Most of us have played with "totally domesticated" house cats, and yes sometimes they like to bite or scratch, to the point where it can hurt and draw blood. But of course it's no sweat because house cats are small.
Now I think it's safe to say that the best tiger trainer in the world may manage to tame a tiger to the point that he's as tame as a house cat. This is a best-case scenario. But considering a tiger's size and strength, that's not nearly enough to make him safe. And a trainer sure as hell ain't going to make him any tamer than a house cat.
Bottom line... never keep a pet that's stronger or bigger than you are. Otherwise, the first time he gets pissed off or overly "playful", you're hamburger.