German Shepherds are quite capable of that and have a *much* higher bite strength than a pit bull, although not as high as that of a Dobermann.
Schutzhund dogs are trained to *not* let go even if you club, whip or shoot them.
Are they all “evil”...or has ~human intervention~ contributed in some way?
Yes, all pit bulls are evil. Human intervention will bring it out. But even without human encouragement, the evil will come out of a pit bull all on its own. They are evil I tell you! Evil! Even the cute loving ones owned by great people that treat them properly.