I don't really buy the argument "TSA has never [...] foiled a terrorist plot or stopped an attack on an airliner.": it could be argued that the TSA measures act

I don't really buy the argument "TSA has never [...] foiled a terrorist plot or stopped an attack on an airliner.": it could be argued that the TSA measures act as an effective deterrent. The thing is that's the wrong metric. The TSA isn't in a vacuum. The metric is whether the security measures have made it hard enough to mount an attack that law enforcement could disrupt it before it began. Right now, I don't see enough evidence to evaluate that either way. However I can say without a doubt that there are plenty of huge issues with the way the TSA is going about things and a lot of things, like body scanners, do not support an effort to score high on the above metric.