... and forcing all taxi companies to use it, and preventing them from putting pointers to their other payment options inside the car.

(Is it just coincidence that every analogy in support of Apple forgets that second bit. Are the analogy writers unaware of that clause, or does it start to sound oppressive so they just leave it out?)

You're right...the "seamless dispatch service" has it value BUT nowhere near the value of the car itself including things like reliability, comfort, space (etc) and certainly not even close to 30%. I think Apple is just pushing this high anchor so that it'll be negotiated down in the future. I believe we'll see this number being gradually notched down until it becomes either very low (in the low teens) or eventually 0 - just like most taxi fleet services now include the dispatch as a standard feature.