Say the car in front of you runs into a stationary object, or something travelling the other way. Instant reaction time wont help as there is no way to decelerate as fast as a colliding car.
Wouldn't the car in front detect the stopped tesla, the lead car would hit the brakes and the cars behind it would hit their brakes at the exact same time?
Assuming most cars have similar stopping distances. There would be no rear end collisions if we had instant reaction time to cars stopping in front us. Rear end collision is the most common collision and attributed to follow distances. Standard safe follow distance is 3 seconds. Standard reaction time is 1 second which means at 60mph you travel 88 ft. Most modern cars can stop from 60mph around 150ft.