I'm not sure how you interpreted the article to be saying google wallet is an ideal solution. It's still an interface, it's just a different interface. It seems to me that the whole point of the article is that both those interfaces are unnatural, and the ideal interface (aka no interface) is presented by square card case: you enter a cafe, you ask for a coffee, you get a coffee. payment is taken care of without you taking your phone out of your pocket or even thinking about it.