This already exists in the UK. The contactless terminal thing, not Apple Pay.
I've been paying at McDs with my contactless card for about a year now.
I also use it at Costa coffee, Spar, WH Smiths, Boots, Greggs, and a whole load of other food retailers (some fast food) and convenience stores. I'm actually looking forward to being able to pay with my iPhone 6 when it's eventually activated here.
The terminals aren't as bulky as that one, and they're on a really long cable.
They're also "Chip and Pin" Terminals, so kinda have to be on a long cable to pass out to the car.
Terminal out, card in, enter pin, pass the terminal back. The cashier doesn't have to touch your card at all - so no risk of anyone swiping the magnetic strip and cloning (something that actually happened a lot over here, before Chip and Pin).
Now, with contactless cards, at McDs they just hold out the terminal, I hold my card there for a second, and it's done - off I drive.
Other places (eg, indoor Mcds, Costa, shops, etc) have the terminal sat next to the till, and again it's just a case of holding the card for a second, and done.
I think the only place I use chip and pin instead of contactless, is the cinema. They haven't upgraded to contactless readers yet.
Link to McDs UK site, and a picture of the terminals they use:
http://www.mcdonalds.co.uk/ukhome/A...tactless_cardpaymentstolaunchatmcdonlads.html
The whole screen is the contactless reader, and there's a keyguard to help shield your pin as you type it.