Standards are a bit lower for driving a car. Also road traffic lights always have the red light at the top which helps a bit. Railway signals USUALLY have the red light at the bottom though this is not universal and not to be relied upon. Some railway signals have a single lens through which red, green, or yellow light is passed.
That and the fact that a train driver needs to be able to act on them long before (s)he is close enough to see the position of the lights.