I just drove 2000km in the last couple days. I have a car with level 2 driver assistance (ADAS). This includes lane assist.
I keep my hands on the steering wheel virtually at all times. I say virtually because I might let go for 2-3 seconds to untwist a bottle cap if everyone else in the car is asleep, not any different than the “knee steering” I did before. However, the car follows the curvature of the road without a problem.
The main benefit of ADAS, to me, is greatly reduced driver exhaustion. Yes, I am paying attention and actively driving the car, however I can focus on the important things.
The ACC ensures I don’t need to worry about fines for speeding due to a heavy foot. It also ensures that I’m “far enough” from the car in front to keep me (and them) safe. Lane assist means I can spend 20% more focus on understanding what shenanigans are going on 5 cars ahead instead of worrying about drifting in another lane.
Do I rely on it continuously? Nope. Do I trust it completely? It’s bad enough that I can’t. However, after driving 2000km, I’m still fresh enough to engage in a conversation in a foreign language with the in-laws, whereas in my prime, 15 years ago, the same trip would’ve put me to bed instantly.
It reduces the cognitive load of driving. It doesn’t make driving easier, however it reduces the mental burden of being a defensive driver.
It’s not unlike ABS. Could I achieve a lower stopping distance by carefully surfing the grip/skid brake pressure? With practice, on a track, absolutely. Do I get greater peace of mind knowing that at any time a computer is checking 500x per second whether my tyres are losing grip, regardless of my state of mind, whether I’m paying attention, am distracted, the road conditions, or which pair of shoes I’m wearing? Undoubtedly.