Not only that, but it removes a key redundancy in signaling: in the typical traffic light design, the state is shown by both position and color. In this one, on

Not only that, but it removes a key redundancy in signaling: in the typical traffic light design, the state is shown by both position and color. In this one, only color tells you whether you should be moving or not. This makes it unusable for the colorblind and much less clear for everyone else. This is a dangerous design.