Jalopnik:

Have you ever noticed cars shutting off one of their front lights to activate a blinker? Well, I certainly have, so to find out why I see awkward one-eyed vehicles signaling turns at seemingly every intersection. I decided to dig into it to find out what’s going on.

I’d noticed this a while ago and thought it was odd and a little annoying. Now that I know the reason, it’s just annoying.