Ludicrous claims by tube train drivers

On a crowded morning train, sorry actually packed liked sardines, the tube driver asked us to please stand away from the doors because proximity to the doors was affecting the motion of the train. Two things went through my mind as my face pressed into the mac of a man in front of me, the angular handbag of a woman dug into my lower back and people to either side held me up - a. how exactly, and b. since when (first time I've ever heard that one in about 20 years of travelling by tube).