It’s illegal in many states for licensed car dealers (new or used) to sell a car w/o an airbag or if it is legal, refuse to do so for fear of later lawsuits. So all those blown airbags have to be replaced.
These days, it’s easy to blow an airbag in a fender bender that doesn’t really damage the drivability of the car or even the cosmetics, but it does screw with the computer and sensors.
And they are expensive. I expect at this point that the theft rate exceeds the accident rate and the black market is now stealing airbags to replace stolen ones, sort of a self created market.
Not only that, front airbags are pretty useless if you are wearing a properly working seat belt.