Touchscreens are not exactly the only way to construct a control in a way that's problematic to use when driving. You can just as well place a physical control

Touchscreens are not exactly the only way to construct a control in a way that's problematic to use when driving. You can just as well place a physical control in a hideous spot in the car, which you can't reach easily, hence making you as the driver bend over and search for the control. Also, physical controls don't necessarily mean that you can recognize them safely without looking at them - buttons can be physical, but still blend into their surroundings in a way that provides no real tactile feedback to your fingers when they find the button. I've seen crazy physical controls in cars that aren't much different from touchscreens with regard to their usability when driving, but still they were technically physical controls and would thus pass your "touchscreen ban". If you want physical controls that actually are significantly safer to use than touchscreens, you need to lay down some ground rules for them as well (reachability, size of buttons, tactile difference from surroundings,...). And that rules out a "blacklist" approach (banning some particular undesired solution) and instead requires a "whitelist" approach (requiring a solution within a defined set of guidelines that constitute what's considered an acceptable solution).