Physical buttons allow for memorized action sequences, though. As long as the input layer has some kind of FIFO buffer, it doesn't really matter how much lag the actual application has. If "call home" is always just "button A, 3x button B, button C" it is absolutely trivial to repeat that without even looking at the screen.
Touchscreens don't work quite as well for this. Even if it allows for input queuing, you often still need the previous screen to finish drawing to have a frame-of-reference for your presses. Even the slightest delay turns into an annoyance, and when it involves some kind of drag-scrolling a 50ms delay already becomes unbearable.
Touchscreens don't work quite as well for this. Even if it allows for input queuing, you often still need the previous screen to finish drawing to have a frame-of-reference for your presses. Even the slightest delay turns into an annoyance, and when it involves some kind of drag-scrolling a 50ms delay already becomes unbearable.