My pet peeve is when there is traffic and people who aren't in a hurry don't GAF about paying attention to how they can do their part to optimize traffic. When the light turns green, I am ready and don't allow a gap in front of me that would mean a car behind me doesn't get through the light. It's really just common courtesy. And you got people who will allow a 5 car gap because they're on their phone, or whatever. Crucify them.
And conversely, I really appreciate people who I can see are on the ball. The other day, I let 2 people in and as I started to let in the 2nd guy, he wasn't expecting the generosity, so he wasn't ready to go. Then I'm thinking, "oh no, I'm gonna let in this 1 guy in and it's going to cost 5 people behind me." But then he noticed, punches it, immediately closes the gap, and then I close behind him, and nobody behind me suffered. He understood the assignment. That was 4 weeks ago and I still think about that guy.