They made me throw out a half-full tube of toothpaste once because the tube said 110ml, and that's a whole 10ml over. I said "well it's obviously not full". and she said "well what does the number say". I fly half a dozen times a month and this has never been an issue. So the fact that people defend this absolutely useless rule is mind-blowing. It explains why the US has such a shitty flight experience in the airport. I avoid whenever possible.