The TSA spends about $5.5b per year on airport security and employs 47k security officers. According to NYT, TSA claims that tighter budgets have forced personnel cutbacks, whereas TSA critics have responded that the agency has failed to plan and failed to prioritize.
Although the cost side is pretty clear in terms of budget and passenger wait time, the benefits are much harder to measure. I have yet to hear of a TSA screen confiscating materials that were to be used in a terrorist attack. Think of the movie that could have been made, with Melissa McCarthy as the heroic screener catching Murray Abraham with a ticking bomb!
Does fear of apprehension by the TSA deter would-be terrorists? The evidence on this front is not encouraging, as reported in today's WP:
Agency watchdogs have documented that undercover security operatives managed to smuggle 67 illegal weapons or simulated bombs past TSA security on 70 tries last year, that TSA officials were unable to properly vet 73 aviation employees who had links to terrorism, thereby allowing them access to secure areas, and the senior managers have a long history of bullying whistleblowers who identify potential problems.Another potential benefit is peace-of-mind for passengers. It could be that even if TSA is totally useless for preventing terrorist acts, passengers may value the service and be reluctant to fly in its absence. The agency is partially funded by passenger fees. In the future it would be worthwhile to (1) conduct research to measure the value of peace-of-mind and (2) figure out a way for air passengers to pay the entire cost.