Want a receipt?

One time I went shopping in the super market I saw I big black plastic bag full of receipts. All ended there since a lot of customers don't want the receipt. Therefore it could be quite smart if somebody could implement a "Do you want receipt?" query when you run through your VISA. Then if not this waste could be avoided. I contacted NETS and suggested the idea but haven't heard from then since some months ago, so it might be stuck or dropped due to the different components that have to communictae - cash register, terminal. Maybe I'll pitch the idea to the supermarket chain rather the company in charge of the payment system.