[hungry_joe]

I lived in Germany for several years; the Germans have some streets where you are required to park with your lights on. With the engine off and the key out of the ignition German cars give the headlights just enough electricity to light up without killing the battery too fast. Motorcycles have much smaller batteries (obviously), so even that trickle of electricity would yield a dead battery fairly soon. It's not so difficult to find a hill to roll start your bike, but it is inconvenient. The manufacturers put low power parking lights on the bikes so the battery will last longer. Alternatively you could just park somewhere else.

As to why you're required to keep your lights on on those streets, I have no idea, but I suspect Germany isn't the only country with such requirements.