This can be offset by the reaction time of computers (assuming braking distance being equal between cars) as the gap is really for reaction time. Or driverless

This can be offset by the reaction time of computers (assuming braking distance being equal between cars) as the gap is really for reaction time. Or driverless vehicles could take it even further where a lead car could communicate with a following vehicle so when the lead cars brakes are applied simultaneously the cars behind do also reducing the delay even further.