You're alluding to the benefits of building interfaces to what people are already familiar with, but touchscreens are still a learned behavior. There is nothing about our physiology that affords anything with a touchscreen beyond touching it.
Touchscreens add flexibility (and lower production costs), but that flexibility comes at a cost. There is no universally agreed-upon usage for them. Certainly not to the degree that "[all] people" understand them the same way. It's all too common to run into a touchscreen-based interface that you haven't seen before and simply not realize you were meant to drag that one element, tap another, or long-press something. Discoverability can be useful, but that quickly loses its value when operating a vehicle -- at least beyond its entertainment system.
Buttons, knobs, wheels, sliders, and levers all have physical characteristics that signal some use. Keep in mind that those can also be (ab)used incorrectly! For example, imagine a knob that you shouldn't turn but must push or pull only. Or perhaps a button that you must twist.
Touchscreens add flexibility (and lower production costs), but that flexibility comes at a cost. There is no universally agreed-upon usage for them. Certainly not to the degree that "[all] people" understand them the same way. It's all too common to run into a touchscreen-based interface that you haven't seen before and simply not realize you were meant to drag that one element, tap another, or long-press something. Discoverability can be useful, but that quickly loses its value when operating a vehicle -- at least beyond its entertainment system.
Buttons, knobs, wheels, sliders, and levers all have physical characteristics that signal some use. Keep in mind that those can also be (ab)used incorrectly! For example, imagine a knob that you shouldn't turn but must push or pull only. Or perhaps a button that you must twist.