I only ever had cars with off, yellow/parking lights, and on as options.
Now, my new car has at least three different settings (Plus high beams) for lights on!! I just discovered the other day that the DRL (daytime running lights) only turns on the front lights, and not the rear. Here I had been using them around twilight because they didn't dim the inner display (it was light enough outside that I wanted the stronger display, but dark enough outside that I wanted more visibility to other cars).
I think that probably some people are like me, and just don't realize that the running lights don't turn on the rear lights like the other, higher headlight settings.