This is not specific to Tesla.
Trivial example: A coworker has a car that has blind spot detection. She knows the manufacturer says "you should still check, it is not 100% accurate". And she admitted that despite knowing this, she does not check her blind spots and relies solely on blind spot detection.
More serious example:
I have a car that has adaptive cruise control. You can get on the highway, set the CC to 60 mph, but if traffic slows down, it automatically slows down and maintains a distance to the next car. It speeds up to 60 mph when the traffic picks up again.
I love it, but for the inexperienced driver, this is dangerous. It requires one to be more vigilant than regular CC. Every so often (rare, but has happened a few times), it will not detect that the vehicle in front of me is a vehicle, and will not slow down. The more you rely on it, the more vigilant you need to be. My wife has never used CC before, and this would be too much for her to handle, compared to simpler CC.
It's a general problem. Tesla is just a convenient target.
I don't know anything about your wife, but that does sound perhaps a touch condescending. Besides that I think you make a very good point, one that many people seem to want to wish away.
That's probably because you don't know anything about my wife :-)
This isn't about my wife. I would never recommend anyone to learn CC on this type of system. They should learn CC on a regular car, and once they're comfortable with that, switch to something like this. You simply have to be more alert for a "safe" CC than a regular one.