thats good thats good, but the relying on nfc phone tap is not since not every phone has nfc
a better option would be either a number code or a qr code the machine scans.
They have a touchscreen on the machine so one hopes they have something setup there.
My understanding is you must have an account and smart phone to use these machines though??
Though I suppose even if you just swipe your credit card and say "guest no account" whatever. Can you put the wrong plug in? They look like they can't fit the wrong standard to the wrong socket?
Pull it out try, if not, put it back and try the next plug head?