thinking about it, I actually like this comparison. You make a good point, in that the physical keyboard is a more accurate tool. But that doesn't mean it doesn't have drawbacks.
The advantage of the digital screen is the customizability and adaptability. If I never use the web browser or music on my iPhone, i can just move those apps off the home row. If my keyboard has a numpad, but I don't need it, I'm stuck with a numpad until i buy a new keyboard.
In my old Land Cruiser, the pull knob to open the vents is right next to the pull knob to open the choke which is right next to the pull knob to activate the hazard lights which is right next to the pull knob to activate the fan. None of them are lit, they all look the same in the dark. We've come a long way since 1981, but the point is that the improved reliability of a physical button means nothing if the ergonomics of the interface as a whole are bad. And it's a lot easier to improve the ergonomics of the system (or adapt them to the user's needs) if the controls are on a touch screen.
The advantage of the digital screen is the customizability and adaptability. If I never use the web browser or music on my iPhone, i can just move those apps off the home row. If my keyboard has a numpad, but I don't need it, I'm stuck with a numpad until i buy a new keyboard.
In my old Land Cruiser, the pull knob to open the vents is right next to the pull knob to open the choke which is right next to the pull knob to activate the hazard lights which is right next to the pull knob to activate the fan. None of them are lit, they all look the same in the dark. We've come a long way since 1981, but the point is that the improved reliability of a physical button means nothing if the ergonomics of the interface as a whole are bad. And it's a lot easier to improve the ergonomics of the system (or adapt them to the user's needs) if the controls are on a touch screen.