I have never understood how this would work in the real world. If my car automatically brakes, I would just get cutoff by other drivers constantly until my car comes to a complete stop in the roadway.
In practice it does leave a bit more following distance than most human drivers, but your worry of constantly getting cut off until you come to a stop in the road is not a real thing. This is partly because the car modifies the set following distance based on speed, so that the same setting is much closer at e.g. 5 mph than at 60.
Interpreting your original comment in that context: AEB only kicks in at a point where maximum braking will result in you barely not hitting something in front of you, or maybe even hitting it at a low speed. Modern cars can stop very fast indeed with maximum braking so in practice this threshold is never crossed under normal driving conditions unless the software returns a false positive. It's not about maintaining a safe following distance—it's about stopping the car at the extreme edge of the safety envelope, beyond which no manual or automatic intervention could prevent a violent crash.
False positives do happen but I think they are very rare or practically nonexistent in good implementations. I've never had it happen with my Honda.
It hasn’t even done the object detected warning beeping when driving on actual roads, which I assume happens prior to the braking. The times I’ve had that warning are parking head on against walls and approach fast, and on one particular 15 mph off ramp that curved sharply such that one drove directly at a sign before turning sharply. It was understandable that it would alert there. No braking.
Assisted Lane keeping is another story, not a fan. Does not account for a ton of things such as the car or truck in the next lane is almost over the line.
So unless the vehicle is fully self driving to the level of an alert good driver, it’s going to mess up. And lane keeping is definitely not claiming to be that.
The lane departure warning beep is fine even although its 90% false alerts for me due to non-lane lines or snow etc, and 9% when two lanes merge and I get lazy about the turn signal with no cars around. But if I were to get more tired or something it could be a helpful alert of last resort to stop driving, hope I never wait that long though because that would be dangerous.
Otoh, I won't use the adaptive cruise control, because the granularity for following distance settings is too coarse, so I have to pick either follow closer than I'd like or follow far enough back that people treat it as an engraved invitation.
I'm not a big user of cruise control anyway, so no big deal. I'm also less frequently driving long distances on I-5, so not in that situation much anyway.