The key word is "unreasonable" - I don't call stopping a bomber from killing people being an "unreasonable" request to randomly search backpacks.
Unless .. you'd rather be blown up ..??
Provided the person being searched could be reasonably considered a bomber. Some 65 year old white dude is not reasonable. Two 20 year old Arab guys with backpacks and shifty eyes would give a reasonable reason to search. But with no racial profiling, all these searches are unreasonable.
Riiiiiight. Searching 1 in 1000 people - and specifically but unofficially avoiding those most likely to either (a) sue for harrassment or (b) actually blow up the searcher - is unreasonable to believe will actually stop these perps. Blowing up on the train, or blowing up in the security line, are going to both garner approximately the same results during rush hour.
I don't understand why anyone believes these empty gestures of "security" actually work, nor do I understand why a growing number of "conservatives" are supporting Communistic methodologies.
The chances of being killed by terrorists while commutting are significantly less than the chance of being killed a host of other ways on the same commute. The only difference is that terrorist attacks are so rare they actually make the news - unlike other commuter fatalities - yet it's the far-less-likely occurrence that people are scared of.
Review your statistics textbook and stay out of my backpack.