My mate had a BMW with a 'service' light on it and couldn't understand it either, seems to be a ploy by car makers to keep their dealerships in work by kidding you into more frequent services.
I have always understood that regular long trips and 'motorway' miles are easier on both the car and the oil than short 'just popping the kids to school' trips where the oil never gets hot, and acids and water soon build up in the oil.