If the 9/11 Hijackings had nothing to do with the 'tools' the hijackers managed to get on board, what did it have to do with? I doubt they managed to overwhelm the aircrew with threats or a spot of harsh language...
I'm no fan of the the current security arrangements, which I think are not particularly well conducted, either in the US or anywhere else that I've been really... But as a European I can imagine what any European countries response to anything similar to 9/11 having happened over here would be, and I doubt it would be very different to the response of the Americans. What would you have them do? The real problems are the queues and the limited resources available to process passengers, rather than the specifics of what checks are applied and how.
In South Korea for example, they're all hot to trot for shoe checking... so shoes have to come off and go through the X-Ray Machine. Passengers get a pair of slippers and you're reunited with your Bally's on the other side... works fine... Just about being organised really and treating the passengers like customers rather than cattle...