Yeah… my wife got super annoyed and our biggest fear was that someone might rear end us or we trigger some serious road rage with someone assuming we are check braking them …. Interestingly on my daily driving around DFW metroplex where I do use TACC occasionally I haven’t had many instances (typically multi lane toll roads with separations). But something between rural roads and high speed limits really upsets “vision only”…
I think it's lack of other cars, and lack of a divided highway. Also undulations in elevation, more common in rural roads than large concrete highways, confuse the vision when the vanishing point vanishes and it can't continue the lane and road lines far enough ahead. It knows there are potentially oncoming cars (no division) and so freaks out and thinks there might be a hidden one right about to pounce over the hill.
It works well in large cities with traffic and straight flat multi-lane highways, where Elon drives, so it was considered good enough.
I favor an "Autosteer without TACC" mode, so the human does the accelerator, and the computer does the steering. There isn't very much phantom swerving.
It's possible this can be done 'manually' by setting a very low speed limit and then overriding it with the foot.