Not only does the car provide repeated warnings, we can pretty clearly infer that—like anyone who has used Autopilot—he had become reasonably proficient at avoiding the warnings. So not only was he warned, he was actively working to avoid those warnings.
(Edit: to those voting me down, please contribute your objections to the discussion.)
Well, the warnings were unrelated and 15 minutes before the crash for once. So that invalids the ignored warnings in that case. I assume the real chain of events will be analyzed now. And the fact that the Autopilot is named the way it is for, presumably, marketing reasons doesn't help.
Exactly, no warnings for 15 minutes. Which means the driver HAD received warnings, understood the warnings, and learned how to avoid the warnings with such proficiency that he did not receive one for 15 minutes. It is not possible to avoid these warnings without being acutely aware of what the car was warning him not to do.
Furthermore, as a licensed car driver, he should know that driving is his responsibility. Nothing a car manufacturer says can diminish that responsibility. Even if Tesla's feature descriptions were ambiguous or insufficiently clear, that doesn't override the responsibility of a licensed car driver to remain in command of the vehicle at all times.
It's not Tesla's fault if a driver ignores the requirements of their driver license AND the vehicle's clearly worded warnings. Claiming that the driver is not at fault because they interpreted the word "autopilot" to mean "I can disregard my responsibility as a driver and ignore the vehicle's very clear warnings" is absurd.
(Edit: to those voting me down, please contribute your objections to the discussion.)