Deep Question.

(Psst: the courteous thing is to hold the door for whoever happens to be behind you or struggling with belongings, regardless of the sex of the door-holder and the door-holdee.)

That's what I was thinking. I hold the door for everybody. Man/woman, black/white, whatever. What I've noticed is that chivalry or politeness isn't always respected, but it's usually accepted. In other words, when I hold the door open for that pretty young thing, she might get a snotty look on her face but she'll sure as hell walk through the door!