When a light turns yellow, a driver has to make a very quick calculus of a number of factors, including estimating stopping duration and distance, traffic prese

When a light turns yellow, a driver has to make a very quick calculus of a number of factors, including estimating stopping duration and distance, traffic presence, penalties, even judgement from other drivers. Some people will place more weight on one or another of those factors. If there is any significant portion of the population that places weight on "this isn't a real red light; it is only meant as a nagging signal" then it seems that the chances of a miscalculation (and high-speed collision) become greater overall.