I believe that the term "autopilot" as applied to Tesla's driver assist system, while technically correct, is highly misleading and tends to raise unrealistic expectations wrt its capabilities.
Why is it "technically correct"? Because is basically does what an autopilot in an airplane or a seaship does: it keeps the craft on a preset course. (Actually the Tesla system even does quite a bit more than this, I am not aware of any aviatic or nautic autopilot sporting a collision avoidance system as advanced as the one used by Tesla - after all they don't need it.)
And that takes us straight to my second point: why is the term "autopilot" misleading? Because it makes people think that they can rely on it most of the time. Which is basicly true in the air or at sea, where obstacles are rather few and literally far inbetween and where the autopilot just frees the crew of the tedious routine task of staying on course. The environment still needs to be watched of course, but obstacles do not normally keep popping up all the time and in a split second.
But this is obviously not true on the road (not even on a motor-, free- or expressway) where the average density of obstacles is higher by a few orders of magnitude. The driver just has to watch the traffic all of the time, even under the best of conditions and no matter how advanced the driver assistance systems of his vehicle may be. Which, of course, makes the very concept of an "autopilot" for automobiles somewhat dubious - on the road it's either fully autonomous driving (at the moment not technically feasible) or it's mostly useless. On the road, the ability to stay on a preset course, augmented with limited collision avoidance capabilities just doesn't cut it.
It is true that Tesla clearly states the limitations of it's "autopilot". The problem is that these limited capabilities are just good enough to mostly work in many situations, thus making the driver more and more careless and daring over time, but can and will fail miserably eventually - typically in a situation where the driver has developed enough of the "contempt that goes with familiarity" for the dangers of relying on the autopilot and has, conciously or unconciously, come to expect a level of autonomy the system cannot provide.
You can call this stupidity, which indeed it is. [sarcasm] Or you could call it bravery (the line between the two being fine at times) - after all the odd bloke pushing the "autopilot" to its limits (and beyond) ist in essence nothing but a volunteer test pilot for a system that really wants to be a fully autonomous vehicle when it grows up but for the time being needs a lot of beta-testing and exploration of corner cases even for its most basic sensors and algorithms.
I wonder if there is somewere on the Tesla campus a monument to "our brave beta-testing customers of blessed memory". In any case there should be one. Dulce et decorum est pro progradu mori... [/sarcasm]