When automobile manufacturers first put vanity mirrors on sun visors, they only put them on the passenger side. Their reasoning was that the passenger was usually a woman who had makeup to apply. The car was being driven by a man and men did not wear makeup.
Why do you figure that the manufacturers eventually started putting vanity mirrors over the driver’s seat? Did they come to believe that men also like to look at themselves in the mirror? Or was it that they suddenly discovered that women also drive cars?