Sometimes I wear a very thin black nylon jacket from Banana Republic. It has to be removed and X-rayed. (It would not set off the detector.) Sometimes I wear it and carry a heavier coat when traveling to a colder climate. So there I am loading up 3 trays with my 2 coats and laptop plus my carryon and my briefcase. Then I have to collect the five items on the other side.

However, if you wear a blazer ("sport coat") then you can walk right through. Logic? None. Just a bunch of stupid rules that embodies the natural instinctive stupidity of government and bureaucracy.