Physical buttons outperform touchscreens in every situation, but they're not always compact and portable. Smartphones and tablets work better with touchscreens because portability matters more, and because no two apps have the same input expectations.
A physical knob, slider, or lever is always going to be a more effective control, but if it's only usable a small percentage of the time, it's pretty wasteful to have it always sitting there taking up space.
There are contexts in which the space and uniformity matters more, like smartphones and tablets, and contexts in which the effectiveness of the control matters more, like in a car.
Cars invented by computer people have touchscreens because they're cheap and easy, and because some computer people don't understand effective interface design. Of course, now cars invented by car people also have touchscreens because they're cheap and easy and because Tesla's getting away with it, so why can't they?
Having a round knob (or slider, but a round knob is standard in cars) always in the same place for volume control is better than having a touchscreen widget that might or might not be visible at all times, because it can be found by touch and doesn't require anyone to take their eyes off the road while driving, and because it can be spun or pushed quickly when needed.
A physical knob, slider, or lever is always going to be a more effective control, but if it's only usable a small percentage of the time, it's pretty wasteful to have it always sitting there taking up space.
There are contexts in which the space and uniformity matters more, like smartphones and tablets, and contexts in which the effectiveness of the control matters more, like in a car.
Cars invented by computer people have touchscreens because they're cheap and easy, and because some computer people don't understand effective interface design. Of course, now cars invented by car people also have touchscreens because they're cheap and easy and because Tesla's getting away with it, so why can't they?
Having a round knob (or slider, but a round knob is standard in cars) always in the same place for volume control is better than having a touchscreen widget that might or might not be visible at all times, because it can be found by touch and doesn't require anyone to take their eyes off the road while driving, and because it can be spun or pushed quickly when needed.
This is really, really basic stuff.