The actual use-case for those is that you can see the brake lights coming on for not only the vehicle in front of you, but at least the one in front of that as

The actual use-case for those is that you can see the brake lights coming on for not only the vehicle in front of you, but at least the one in front of that as well, since you can see through the passenger space of the car in front of you. So it's not just a psychological issue here, but an actual visibility issue. The same thing applies to blinker lights on side-view mirrors. They are much more visible at wider angles.