How to turn these features off varies by manufacturer. Some have specific buttons on the steering wheel or elsewhere, others have 'virtual' buttons on the display screen. Others have a menu for driver selectable features you can adjust only when the car is in park. Sometimes there are features they won't let you disable. If you get into something like a rental car from a manufacturer you haven't previously driven, I can certainly see how these features can become a huge distraction.
Can recall driving one car a couple of years ago where if you change lanes when it thinks you shouldn't, the steering actually becomes tighter/stiffer to operate. When it first happened I thought the steering was malfunctioning. Certainly turned that feature OFF as soon as I could. I can see someone not familiar with it in some emergency situation would tend to apply a lot of extra force on the steering wheel and perhaps even run themselves off the road. The last thing I want in any emergency situation is to be fighting against what the car incorrectly determines as the way to resolve the situation.
It seems like some engineer/design person invented these features that sound great in theory, but in real world driving situations don't work nearly as well. I seemed to recall some articles that mentioned issues with 'self driving' cars getting confused with road construction temporary lanes. Have never driven a car with any type of self driving capabilities and not sure I would have any interest in using that feature.