You put your finger on the nub: these freedom-sapping measures don't even produce the promised safety. Anyone who wants to get a bomb onto a subway can easily enough do so, search or no search. Parts can be split across multiple couriers and hidden inside boom boxes, for example.
I've taken my jacknife on enough planes to know that airport security is a joke. (In my case, the knife is part of my keyring, and I keep forgetting I have it in my pockets until too late.)
On a recent thread, I described how easy it was to enter a 'secure federal installation' without showing any ID. By observing the 'security measures' for less than an hour, I saw how easy it would be to defeat it and enter the facility with ANYTHING that I wanted to get inside.
'Security' in this country is a huge and expensive and dramatically ineffective joke, but does work fairly well as a jobs program and training ground for jack boot wannabees.
You don't have to blow up government facilities to create terror. In fact, our unguarded civilian facilities provide more than an ample supply of targets. Why haven't they been hit?
I'm not really sure what it means that we have not been attacked successly since 9/11. Is it luck? Is it lack of interest? Is it a lack of will or capacity?