It is not so much that as Americans are hooked on convenience. They HATE the lines at airport security as it is and frankly I don't blame them. If they had to quadruple (or worse) those wait times while they underwent a personal secondary interview as to why they were getting on an airplane, they would go absolutely bonkers. We could never pull that off here. But interestingly enough, I remember an interview with the security chief of El Al right after 9/11 when asked what they were going to do differently security wise, he replied "nothing".