You can't really put "better touchpad" on a label... or can you?
That's a real problem in many situations: users are often under-estimated (they are also often dumb, which doesn't help).
Apple doesn't put "better touchpad" on their labels either. It's just very very obvious that they're better.
Exactly. Everyone knows Apple has better touchpad, but nobody knows that about some random PC manufacturer. How will they signal that he has better touchpad in order to justify the higher price?
There are plenty of PC manufacturers that aren't "some random PC manufacturer". ThinkPad, Asus, Acer, HP, Dell. They are known brands that can easily maintain reputations.
I would also wager that the sort of customers who are willing to spend more for interface refinements like an excellent touchpad already use Apple hardware at a higher rate than the general population, further shrinking customer demand for good PC touchpads.