> 9/11 certainly was pretty unusual, but packing a suitcase with explosives and nails and hauling it into a crowd of civilians is the sort of thing that happens fairly regularly in some parts of the world.
Sure, but the places where it happens anything that could even remotely be described as fairly regularly in parts of the world where the social and economic conditions and legitimate political outlets for dissatisfaction with those conditions are all vastly different than in the part of the world that has the TSA doing screening at airports, i.e., the US.
While it has happened at times in the US (e.g., Boston Marathon), it doesn't happen enough that the expected number of times it would be expected to have happened in airport lines if such events were even distributed among similarly-sized crowds would be anywhere close to 1.
Sure, but the places where it happens anything that could even remotely be described as fairly regularly in parts of the world where the social and economic conditions and legitimate political outlets for dissatisfaction with those conditions are all vastly different than in the part of the world that has the TSA doing screening at airports, i.e., the US.
While it has happened at times in the US (e.g., Boston Marathon), it doesn't happen enough that the expected number of times it would be expected to have happened in airport lines if such events were even distributed among similarly-sized crowds would be anywhere close to 1.