Air lines

Recent US research by the Harvard School of Public Health suggests there is no evidence that airport security (you know - those lines where you wait to have your hand luggage screened, and sometimes even take off your shoes and belt - depending on which airport you're at) actually makes flying any safer. While it may well do, eg the US Transportation Security Administration (TSA) reported that more than 13 million items were seized in one year, there is no evidence that these items could have been used to harm aircraft or crew. There were also no comprehensive studies which evaluated the different forms of security nor testing accuracy.
But it would not do to "do away" with the methods, especially the explosives trace wand. I still have fond memories of S doing "trace wand tango" and of the story of a man who put out one arm, then a leg, and then his other arm - and was then told to make a noise as though he was a plane - much to the amusement of his girlfriend and mother who had come to the airport to see him off and were making suggestions to the man with the wand).