First my apologies if you've already read an earlier version of this post. I originally posted it in a different thread but this thread seems more relevant...
I live in a red rock desert with wide open vistas and many dead straight two-lane highways. I sometimes leave early in the morning to drive 250 miles of mostly wide well-striped two-lane roads to Salt Lake City (and back same day). In that distance we can experience more than 25 instances of severe phantom braking - each way!. Leaving in the dark, oncoming headlights as far away as 200 yards or more (really!) can initiate sudden violent braking dropping speed from 65 mph to 40 mph in less than 2 seconds. Other times approaching bridges, guardrails, highway cuts between earth berms, oncoming trucks (usually dark colored) or sometimes absolutely nothing (obvious) will cause an event. Most, but by no means all, braking events occur in poor lighting or with strong side light shadows such as nearing sunrise or sundown. Flat lighting seems to reduce but not eliminate the incident rate.
I've endeavored to record many "bug reports" and have force-saved dash cam video but nothing out of the ordinary shows in later reviews. I've recalibrated the cameras several times with no apparent effect. A recent software update to 2021.36.5.5 has also had no apparent effect.
So, here's my personal take on what could be behind phantom braking:
1. It would make sense for Tesla's TACC to use the same object recognition algorithms as FSD. When dealing with self-driving I'm sure Tesla is going to be ultra-conservative in their assessment; they don't want to be accused of causing collisions. Hence, braking is deemed preferable to incorrect analysis that could cause a potentially fatal accident. (Although phantom braking can and likely will lead to rear end collisions.)
2. The forward looking cameras used for distance in our MY appear to be spaced no wider apart than human eyes, maybe less. In every other vehicle I've owned with "adaptive speed control" the traffic aware cameras have been spaced upwards of 8"-12" apart. This wider spacing offers far better distance/range analysis. Tesla seems to be counting on their camera quality and range finding technology - but it's not there yet.
Anyway, neither of these conditions are likely to be resolved anytime soon so I end up driving my high tech automobile as if it was 1960.