I've heard a story from a friend that was in an accident like that. A police officer who did the paperwork smiled and said "It's the most common type of accident - people just stop paying attention to the car in front that started moving, and develop sort of a blind spot to that".
I drive for several years, and can say my brain relies heavily on this sort of predictable stuff like "that car has free intersection in front of it, it will move forward".
