Well, I mean, I did potentially traumatize a schoolgirl, which makes me feel rather bad. But less bad than if she's successfully put a steel and plastic wall in my path? I was particularly annoyed because I live in a very popular bikey area, and I was in a bike lane.

There's actually a trick to train yourself into so you don't even have to think about looking for people on bikes! The Dutch reach! You just open the car door with your far hand, which causes you to turn
your head towards the window and makes it easier to spot people approaching on bikes from behind. Diagrams here: https://www.dutchreach.org