That had always been my take as well until a couple of years ago. I was visiting a friend in Germany and we were both bitching about the inconveniences of the security measures associated with air travel. I pointed out the uselessness of them by stating that no hijacking will ever happen again anyway for the reasons you give. He disagreed so I said it already happened on Flight 93. My German friend looked me straight in the eye and said, "Yes, but those were Americans." I thought about it a bit and decided he's right. A flight without a preponderance of American passengers could probably be hijacked.
As a matter of fact, not long after that there was an attempted hijacking of a train from Belgium to Paris. It took three American young men - not much past boyhood - to tackle the terrorist. It sounded like all the other passengers just sat there - except for an Englishman who helped and later said, "Who knew - courage is contagious!"
“My German friend looked me straight in the eye and said, ‘Yes, but those were Americans.’”
Cool. I take that as an amazing compliment to US.