Sad situation, I see the range of emotions in the many responses to this thread and as a Model S owner I share them too. Condolences to this man's poor family and may he RIP.
Speculating before we know all the facts can be unproductive, but also therapeutic. Also, it's all we can do at the moment.
Reading the accounts of the incident it sounds like the Model S driver was probably doing something else, and was counting on the car to autonomously drive down what was probably a not-super-busy road at a pretty good clip. Again, speculation, but it seems like the only set of facts that makes sense in light of the lack of braking. I don't believe that the driver "couldn't" see the truck, rather it seems much more likely they were not looking up at all (Harry Potter playing on a laptop?), or possibly asleep. This sounds like a plausible scenario for someone who was clearly using AP a lot and had probably gotten very comfortable with it.
While this was obviously not a good choice (if the above is remotely accurate, again speculation), it underscores how quickly a sophisticated system like AP can inspire a false sense of security, despite the many warnings. This is part of our human nature even with the best intentions, much less a situation where the warnings are seemingly deliberately disregarded. This reality is important to recognize for companies that put these technologies in the hands of the public. Calling it "beta" in a production vehicle is a dangerous game.
I'm sure they got a very detailed account from the truck driver. An analysis of the scene will determine whether it was likely he saw the oncoming car, and may help explain why he thought he had time to complete the turn (or, as I've seen many trucks do, just assume that because they are big, you are going to see them and slow down for them). While he may share some of the blame here, it seems like he would have had to have been turning for awhile in order for the Model S to hit mid-trailer, which suggests at the least that this was probably not a sudden-swerve scenario that could have caught even an alert driver unawares.
As for AP itself, while it's called "beta" and its limitations are explained to drivers, this situation still represents a failure of both AP and the proactive safety systems of the vehicle to avoid or reduce the severity of the collision, and I expect internally in Tesla it will be treated as such. If it is true that the brakes were never applied, it suggests AP never attempted to alert the driver even in the last few seconds prior to the accident. While there may be specific reasons for this tied to the limitations of the technology, that means the technology needs to be improved. There are a lot of trucks out there, and a lot of highways with turn lanes. Even in situations where it is the driver's fault for not paying attention, the ultimate reason for the existence of these technologies is to figure out a way to save him despite that.
While the event is tragic, this man's death may very well save the lives of countless others as these outlying situations give new data inputs to help engineers from Tesla and other manufacturers make semi-autonomous driving systems and pro-active safety systems perform increasingly better as time goes on. God rest his soul.
