Actually, a least some cars (probably more than you think)/have some sort of “emergency” breaking signal, which often result in the usual breaking signal blinking for a while. You need to seriously slam the brakes to see it though. E.g: https://m.youtube.com/watch?v=j_osu1WgGMU
There is also a nice technology connection video talking about braking lights for electric cars and in general, which can be dangerous.
I’ve seen some people play with the programming of BMWs. I was really impressed with one I saw that had 3 levels of lighting. It didn’t affect the actual brake lights but instead utilized the rear fog light. Normal braking was just the normal lights. Moderate braking turned on the rear fog lights. But when he slammed the brakes, the rear fogs flashed.
I was also pissed to be in traffic that allowed for all 3 modes in a few miles.
That’s frequently not the choice of the driver. An adequate follow distance provides a luxurious amount of space for someone to merge into, forcing you to slow to extend the follow distance, which allows more people to merge… etc.
