Actually, this is not true. Here's a first-hand story, from the days before TSA put ziploc bags at inspections. So . . . I don't have a ziploc bag, and I left a little 50 ml bag of some funky French "scotch" (can you believe it!) in my carry on. TSA found it and confiscated it, both of us joking about the notion of "French scotch", me bemoaning its sorry fate. So anyway . . . my wife and I are eating sandwichs purchased from a deli, before we board. And lo and behold the sandwiches are in ziploc plastic bags. So I go back to the TSA guy and I wave the bag at him and he points to the wastebasket. There is my little bottle of scotch in the bottom with all the other trash. I plucked it out and off I went.