It seems to be solved quite well on my 2014 Honda:
- qruise control keeps the speed, but lowers it if there is a car in front and keeps a configurale distance by automatically accelerating and decelerating (and braking if needed). It uses radar as opposed to Tesla's camera-only solution which is vulnerable to blinding low sunlight (which seems to be a possible culprit in this case).
- lane guidance steers to keep the car in lane if i switch it on. But if I let go of the wheel, it will soon give an audible and visual warning and soon disable itself.
This for me is unintrusive enough to use on a highway, yet it is strictly "driver assist" not self-driving, so I will not lose focus.