The unfortunate thing about people is we acclimatise quickly to the demands of our situation. If everything seems OK, the car seems to be driving itself, we start to pay less attention. Fighting that impulse is extremely hard.

A good example is ADHD. I have severe ADHD so I take meds to manage it. If I am driving an automatic car on cruise control I find it very difficult to maintain long term high intensity concentration. The solution for me is to drive a manual. The constant involvement of maintaining speed, revs, gear ratio, and so on mean I can pay attention much easier. Add to that thinking about hypermiling and defensive driving and I have become a very safe driver, putting about 25-30 thousand kms on my car each year for over a decade without so much as a fender bender. In an automatic I was always tense, forcing focus on the road, and honestly it hurt my neck and shoulders because of the tension. In my zippy little manual I have no trouble driving at all.

So imagine that but up to an even higher level. Someone is supervising a car which handles most situations well enough to make you feel like a passenger. They will switch off and stop paying attention eventually. At that point it is on them, not the car itself being unfit. I want self driving to be a reality but right now it is not. We can do all sorts of driver assist stuff but not full self driving.

You seem to have missed the point. Whether or not you think that would be an easy job, the whole reason you'd be there is to be the one that takes all the blame when the autopilot kills someone. It will be your name, your face, every single record of your past mistakes getting blasted on the news and in court because Elon's shitty vanity project finally killed a real child instead of a test dummy. You'll be the one having to explain to a grieving family just how hard it is to actually pay complete attention every moment of every day, when all you've had to do before is just sit there.