Apple Pay is somehow both confusing and blindingly simple at the same time.On the one hand, mobile payments have been around for so long without gaining any traction whatsoever - so how can Apple do anything different? On the other hand, when you see it in action, this couldn't be a simpler system. Tap the phone or press a button online and you're up and running.The confusion comes in the setup, where you'll be able to add as many credit and debit cards as possible to your Passbook to use at checkout. How do you get them on there? Can you use any of them?