This is a horsemanship/ignorance flaw, not an inherent flaw in the equipment. As I'm sure you realize. ANY piece of equipment can fail to function as promised or there can always be situations where the equipment did not help. (how many people have a story buried somewhere about a cop telling so-and-so that if Billy Bob HAD been wearing his seat belt he would have died?) This is inherent. But when you add high-velocity inflation of airbags in close proximity to vital organs and fragile necks, you have the potential of unintended consequences. This is why airbags today are very different than airbags that first came out.
And I gave the examples of martingales only because one can make one so short as to be very dangerous to the ability of a horse to keep upright when things go awry.