Airbags didn't deploy in front end collision?

I guess we should all double check our seatbelts since the airbags are at the mercy of a computer’s algorithmic computations. The engineers are the pros when it comes to designing these systems but I’m now wondering where the fine line is between the airbags working or not working. The “gray” area always bothers me a little but I’m glad the airbags are there at least. I have had a couple of family members and friends who have walked away after a bad crash and the airbags worked as advertised.