Courtesy, to me, is an expression of me. I hold doors, elevators and stop for pedestrians. And especially if it is raining. It doesn't matter if they're carrying a baby or elderly or able bodied. I just do it. I do it because it reflects my values. I would never call out someone who failed to say thank you. I don't do it for them, I do it for me. I wouldn't embarrass myself by making it look like I did the right thing for a thank you or for attention from strangers.