I think in many of these situations, the victims never saw the knife to begin with. The attack was on a completely unsuspecting and defenseless person. Kinda hard to defend what you can't see. So, I ask, what technique isn't working? How many arts teach how to defend against an attack that you can't see to begin with? How can we even assume that these victims were even trained in any sort of knife defense and were even attempting to utilize such techniques? These victims didn't seem to be trained to me. How can a technique fail if you don't know any techniques? Am I missing something here? Maybe I'm just tired.
James
While I agree with all your points, I think it is fair to say that most "knife defense" that is presented in many martial arts fail to address these types of "prison shank" attacks, including kenpo.