This approach - giving your identity to prove you're going to pay for the item - seems overly careless in the age of privacy violations. Another system - where

This approach - giving your identity to prove you're going to pay for the item - seems overly careless in the age of privacy violations. Another system - where you can only give the proof, without the identity - would be better, but it's unclear at the moment how that could be reached. Besides, putting an item on the shelf in case you don't have enough cash has another nice feature - an opportunity to think twice if you really need that item in the first place. If you pay too easily, it's harder to save.