See Canuck's post about the "but-for" test. Just because autopilot (or TACC) was on, doesn't mean it was the cause of the crash by default. That seems to be what you are arguing and people are disagreeing with.
If the system malfunctioned (just like how old-school CC can malfunction) then it can be the cause, but if it didn't, then it wasn't the cause.
As for delineating the differences:
CC: can accelerate or decelerate to a set speed (using application or non-application of throttle and sometimes gearing)
ACC: can accelerate or decelerate to a set speed or in response to traffic (using throttle/gearing/brakes)
AP: TACC with lane keeping (throttle/gearing/brakes/steering)
All of the above requires constant monitoring and the user to react to condition changes outside its parameters.
Let's say you crashed into a stationary vehicle because you weren't paying attention to the road and didn't brake in time. In all cases (unassisted, CC, ACC, or AP) your inattention was the cause of the crash. With the but-for test: you would have crashed into the car regardless of the existence and activation states of the various possible systems.
Then let's say you crashed into a car that was going at your set speed (no change in traffic conditions) because the system glitched and suddenly decided to accelerate (such that you couldn't have braked in time). Then the system (regardless of if it was "old school CC", ACC, or AP) was the cause of the crash.
See the difference?
And as others pointed out, CC/ACC glitching in such a way is pretty much unheard of (a quick google couldn't find any proven cases of this happening, only talk about a debunked myth of someone successfully suing an RV manufacturer after a crash from leaving the RV unattended while CC was active). It would take more than just a driver's claim to believe this was what happened.
That's the problem, though, you keep trying to bring a legal standard into a non-legal standard discussion. A legal standard is there to assign responsibility. The posts that I was referencing were not speaking to a legal standard, they were speaking to a technical standard, and those statements were patently incorrect. I 100% agree with you that the responsibility is still on the driver and that they are ultimately responsible.
However, this thread is about how AP (supposedly) malfunctioned, as (as I posted in my initial post on the subject) stated, the crash was caused by AP, not by the user. Others are trying to assign the cause to the user and that is simply not the case.
That said, let me address your statement that "your inattention " was the cause of the crash. That is a secondary cause, or contributing factor if you will. Not a primary cause. CC, ACC or AP accelerating into the back of a vehicle is the cause of the crash. CC, ACC or AP braking hard and causing a rear end collision is the CAUSE of a crash. This is a simple concept and it boggles my mind as to why so many people have a hard time grasping it.
You can shuffle off the cause however many steps up the chain you want, but that is specious at best. If you start moving up the "cause" chain, where do you stop? Like I've already posted, you can move the "cause" up to the user, but why not move it up to the programmers of the system, or to the chip manufacturers or to the raw material suppliers? Hell, lets just move it on up the chain to the big bang - because we can do that if we don't mind moving the cause and effect from the primary cause to any secondary cause we want.
To use the but-for test you are quoting:
He would not have caused the crashed, but for the AP accelerating.
AP would not have caused the crashed, but for the programmers making a mistake.
The programmers would not have caused the crash, but for the chip manufacturers making those chips!
The chip manufacturers would not have caused the crash but for those raw material suppliers!
The raw material suppliers would not have caused the crash but for the comets crashing into the earth!
The comets would not have caused the crash but for gravity coalescing the atoms into a comet!
Etc...
I think we would all agree each of those are silly in the extreme. When you are assigning responsibility in a court, you need to use the but-for to find the primary person RESPONSIBLE. That does not find the cause as stated here in this thread (and others).
I suppose we are having a bit of a communication breakdown because we aren't separating a failure mode from an "as designed" mode as well, so let's break that down:
As posted in OP and assuming events happened as described (I'm not commenting on the likelihood or validity of the OP statement) something unexpected and improper happened. Because something failed to perform as designed (in this case, the car accelerates into the back of another vehicle), the cause is most definitely the AP (or TACC), not the user.
In the case of old school CC, where the user just lets the car accelerate into the back of another car, then the cause is the user - the user knew ahead of time that the CC would not brake for a car in front of it and knew ahead of time that the CC would not slow down.
Why are these two different, when the result is the same? Because it has to do with expectations and design features. TACC is designed to slow down for traffic and the expectation is that it will do so. Its entire purpose (The TA in TACC) is to prevent the car from accelerating into the back of another car. Is the user responsible for monitoring that functionality? Yes, absolutely. But they are not the CAUSE of the crash in the instances of TACC, whereas they are in the instance of CC.
Assign blame all you want and I will agree with you, but please don't assign cause to the wrong parties. Although, I find it pretty annoying that the holier-than-thou parties have to always show up in any thread that indicates there might be a problem and continually spout off about how "It's only beta."
