Yes, it's a small thing, but a modicum of civility to others when driving seems sensible. I am amazed at how many people simply pull out - when I have stopped to let them in, or made room for them to turn - without waving or acknowledging the 'favour' in any way.
I end up irritated that I have 'helped' a rude twit, instead of thinking I've made a small gesture that might have helped someone.
It is now so common that I am reconsidering being considerate - why bother? I'm in a hurry too.....