I can remember going off to college at 18 (I grew up in rural TN), and just being shocked at other students not doing what I considered to be most mandatory of personal curtesies. Removing ones hat while dining, in class, entering a professors office was one.

I do lament that I've let myself slip over the years when it comes to door holding. Several empowered girlfriends and the office culture have slowly worn me down. I always feel bad when I realize that I;ve dumped the door on some poor person with an arm full of groceries.