The news reports no effort was made to apply the brakes
So:
Driver not paying attention
or
Driver incapacitated
That's all there is to know.
When I engage Autopilot I get a warning message on the screen briefly saying "keep your hands on the wheel", so that's what I do. Anyone who is watching a movie, texting their mates, turning round to sort the kids out in the back, and so on ... and on ... and on ... is
not driving with due care.
If you have your hands on the wheel, paying attention, whether you are using autopliot or not, you just don't drive into stationary objects, its that simple. If AEB kicks in to assist me in stopping, that's great, and may well mean that whatever action I take happens faster and better, that's great. But until the car is Autonymous I am still the one driving it.
If the car beeps when I start to change lanes or, better still, swerves safely, because there is something in my blindspot that I didn't see, or something moves towards me dangerously, that's great. But, either way, I have my wing mirrors offset, as recommended by motoring organisations, so that I have to move my head slightly to use them such that I can see the blindspot.
Now, if I read that a driver had his foot hard on the brake and AP drove into a stationary object ... or off the edge of the road into a tree ... etc., THEN I would be concerned.
Any part of that that you don't understand? please just ask for clarification.