Did you drive with such a system? If you did, you would know there’s a HUGE difference between having to manage minutae (just keeping yourself in a lane is surprising amount of work) and being free to pay attention to your surroundings.

Your cognitive load is lowered by Autopilot enormously. You can pay better attention to what’s going on around you and anticipate issues (say, a car that drivers weirdly in front of you) because you’re not busy with the low-level driving.

Part of that is that you see a difficult road stretch coming up and disengage the assist IN ADVANCE - becuase you’re not a complete moron, know the lane assist is for driving in highway lanes and the thing you’re approaching is decisively not one.

This is the automation paradox, and one that Tesla itself has been facing with their assembly lines.

If you over-automate something you end up having to spend more time supervising and fixing it than if you'd just done the thing yourself in the first place.