Absolutely it is (I always double check the mirror and crack the door first, even as a passenger) but it's defense in depth, and as a cyclist, if someone's goin

Absolutely it is (I always double check the mirror and crack the door first, even as a passenger) but it's defense in depth, and as a cyclist, if someone's going to open the door anyway, I'd rather be able to see it that assume they've seen me. I have lights, but as a driver, I also know that even the brightest bike lights can by surprising easy to miss. Also, speaking as a cyclist, it can be surprisingly hard to see an opening car door in the dark. The side of the inside of a door is the same colour as the bodywork, so this is not as obvious as you might always expect. It's also not only cyclists who can see this - cars with their light on will see it too, and since I'd quite like my car to continue to have a full set of doors, this is a win for me too. Also, the car carries passengers and is not always driven by me. While obviously, I am completely perfect and am obviously physically incapable of fucking up, I cannot guarantee they will not open their doors badly, so I might as well make an effort to mitigate it in case they do.