It seems rather obvious to me the "Real Reason" for the mechanism of the car door is so one "Does Not Have to Hold the Button" in order to close it. Can you imagine trying to shut the door with two armloads of groceries if you had to hold the button in, in order for it to latch?? As previously mentioned the advise I have always read from "British Authorities" is to hold the bbls in left hand & lift stock with right hand, neither thumb can thus even reach the lever.
Miller

Miller/TN
I Didn't Say Everything I Said, Yogi Berra