I fully expect people like you pop in here when some accident happens. But I can tell you this capability has been there and I have seen it in action myself many times, where it slowed down even before the car in front of me reacted. Why is my car slowing down head-scratch moment, and then it becomes clear that car 2 cars ahead of in front has slowed down.
Additionally my car stops daily from 50 to 0, for cars stopped in red lights without missing a beat, as long as there is a line of sight to the stopped car for atleast say 30 feet.
I bet this failure is a corner case that only happens because of the front car moving away at the last minute exposing the stalled car at the last second or two, and the car does not have time to confirm if it is false positive or not.
If it saved 100 accidents, that is 100 less than what would have been if this capability had not been there.