With my previous experience in counter terrorism and intelligence, I will tell you that I KNOW (though actual reports are classified) that the security measures in place are a deterrent to many terrorist attempts to attack commercial aircraft. There have been more attempts than have been publicized that have been caught and some groups that turn to other targets because they view commercial air as too difficult.

That said, as with any organization, procedures may be well thought out and planned, but the problem is with the implementation. You are limited by how trainable your people are and their level of professionalism. You also have a tedious job, with a great many of complaining and irate passengers to deal with. I am surprised it works as well as it does. As for some of the methods or technologies, they are in response to specific attempts at attacking aircraft. It is a constant battle with the terrorists to keep ahead of their innovative methods. But if anyone thinks that they are not trying, they are. This is only my word, but the word of someone who until a year ago had complete access to all of that information.

I know it sounds a bit corny, but put yourself in the shoes of someone trying to manage a system which is responsible for maintaining security for such a large and geographically distributed industry, and with the tools that are available with a real and frequent threat. Like I said, I am surprised it works as well as it does.