In our reading group last night, we started talking about trade-offs and the like and I put forward the following argument, to which Jeremy H. wondered whether there was or could be any empirical evidence. If anyone knows or wants to try to write it up, go right ahead. I'm happy to be shown a good argument like this that's been made before, especially if it has empirics to go with it.
Assuming that the goal of the increased security measures at US airports since 9/11 is to prevent deaths due to terrorist or other attacks using airplanes, might it be the case that the increase to the total cost of flying that the longer lines and increased intrusiveness and inconveniences of their policies have created has caused a good number of people (on the margin of course) to switch to forms of transportation, such as driving, that are far more dangerous? If so, isn't it possible that the additional driving has killed more people than would have been killed by attempts at terrorism on planes?
This is particularly relevant because of the examples we've seen of failed security measures where the bad guys were subdued by quick thinking passengers. This suggests that the real way to reduce deaths is by more vigilant, if not armed (an idea that Archie Bunker had almost 40 years ago), passengers and that even if these costly security measures were non-existent, we would be unlikely to see a repeat of 9/11.
So to the degree current security measures impose costs sufficient to cause a good number of people on the margin to drive and simultaneously do little to reduce the likelihood of terrorist-caused airplane deaths, they might be having the ultimate effect of causing more deaths in the US than we'd have without them.