Half of it is Apple's Execution. The other half is the challenge of working around patents and working with second-rate electronics.
FWIW only Apple trackpads made me drop lugging a mouse around. This big-ass, ice-like sliding, smooth surface is a wonder to work on for hours. It seems PC manufacturers conspire to make the smallest, most post-10-min-of-use grinding surface ever: not only the size makes it a pain to aim, having to fight against the surface just kills it.
Don't know about PCs, but the current and last gen of MacBook Airs uses the Broadcom bcm5974 touchpad controller, and I believe the MBPs do as well. The Linux "synaptics" driver drives a lot more than just Synaptics chipsets these days.