I see my share of car crashes (they are RARELY accidents, as most can be avoided by proper driving....unless the obvious circumstances) and air bags fail fairly often. As do ABS brakes. Alot of people put alot of faith in those 2 safety features. This isnt out of the ordinary.
The average car today has 6 airbags, and luxury cars can have up to 12. Sometimes, for some reason, the airbags will deploy after the crash. Other have a secondary explosion. Interesting fact, you will never remember the bag going off if you are in a car crash.
The more technology the more room for failure IMO