Well, in aviation, they do go to great lengths to let the pilot know which mode they're flying in and transition into and out of that mode has it's own protocol, training and feedback. Indeed the whole surepticious engagement of the MCAS system on the 787-MAX aircraft, and in particular not including updates for pilots in training to deal with what to do when that system fails -- i.e. awareness -- is probably going to end a few careers at Boeing. That seems to be an example very close to the Tesla situation. The AF447 crash in 2009 has a spookily similar pathology -- confusion about automated flight control modes. Both incidents were
awareness of automation issues, one with it being on, one with it being off (more or less).
Tesla is banking on a beep and/or input control shake covering them for mode change awareness for a completely novice, untrained and uncertified driver. Is that a reasonably assumption?
Edit: There were other (tragic) factors in the AF447 crash, but in that case, if they'd re-enabled autopilot and let go of the controls, they would have very likely survived.