airbags are not actually safer, the were invented to get cars through the euro Ncap safety test, if you are sitting perfectly in the seat and don't tense up they work beautifully, but for example if you have your head turned looking left at the round about and you are leaning forward over the steering wheel and someone hits you from behind (very common) the airbag will push your head round and break your neck.
basically if you are a car maker, you sell more cars if your car is safe, your car is considered safe if it gets a good result from the safety test so all you have to do is protect the crash dummies, crash dummies never apply the brake so they are never thrown forwards over the airbags before the impact.