Exactly. Why on Earth would they default to touching something away from the screen that's an imperfect map to it when they can just touch the thing they want directly? I've seen so many people saying they don't understand and would never use a touchscreen on a laptop, and I just have to think they've not really been around non-technical adults or children.
because it’s much further away. if you have your desktop adapted to be keyboard-driven, things that are far apart in 2d space may be very close in logical user-event space. same holds here. moving a single finger and clicking usually requires much less movement. and movements compound.
and your observation is not at all universal. moving a vehicle is much easier via a mapping to a more abstract control, as opposed to controls resembling the effector. this abstract control also fits many vehicles. the same is true for all sorts of controls.
Because the ergonomics are shit. Holding your arm up is tiring.