It's a bit of a stereotype, but the Germans are known for their devotion to following the rules (laws). I recall reading an account by an American who was taken aback while driving in Germany when a fellow motorist followed him off the autobahn to chastise him for passing on the right, which is apparently illegal.
Perhaps it is easier to get people to be willingly vulnerable on the roadways when the folks operating the motor vehicles are following the law. I've only lived in one place where the police actively enforced the traffic laws and it happened to have the highest rates of bicycle use in history. Sadly, the police changed their priorities and the bikes all but disappeared. Maybe it's just a coincidence.