I think you dismiss styluses too quickly here. You can be much more precise with a stylus than with a mouse. Just because the tip of the stylus isn't one pixel in diameter, it's probably the most accurate form of input you can get. That's why Wacom tablets are so popular.
Also:
> Even a conventional touchpad on a cheap laptop has better precision than your finger does.
A conventional touchpad...that you use with your finger...? Am I missing something here? How is a touchpad more accurate than touching a screen?
With most touchpads/trackpads, you can tilt your finger by a few degrees in any direction to fine-tune your aim before you click. This enables pixel-perfect clicking when you need it. (Use the physical button when you do this, because tapping will ruin your aim.) With touchscreens, you can't fine-tune your aim before you tap. You just tap, and hope that you hit the correct coordinates.
And with most touch-screens you can (un)pinch to zoom in and get as accurate as you want/need.
The entire desire for 'pixel-perfect' clicking on a static UI is a symptom of trying to shoe-horn touch into interfaces not explicitly designed for it. Has that ever worked?
Also:
> Even a conventional touchpad on a cheap laptop has better precision than your finger does.
A conventional touchpad...that you use with your finger...? Am I missing something here? How is a touchpad more accurate than touching a screen?