David Canton's regular IT column in the London Free Press is about the practice of printing full debit and credit card numbers on receipts. (See: London Free Press - David Canton - Printing card data not smart.)
This is a practice that really bugs me. In three days in Toronto last week, every debit and credit card receipt I accumulated had my full number and expiry date printed on it. I was in Toronto for a Canadian Institute conference on Privacy Compliance, which I co-chaired. The topic of receipts came up in discussions with the Assistant Privacy Commissioner of Canada, the Alberta Commissioner and the British Columbia Commissioner. The Alberta Commissioner, Frank Work, discussed the incident that David mentions in his column and one of the more interesting things he discovered in his investigation: there's a black market for these receipts and they are $25.00 each.
The assistant federal commissioner, Heather Black, mentioned that the Commissioner's office had canvassed most of the POS suppliers in Canada, who assured them that they are rolling out upgraded machines as fast as they can. Not fast enough, in my personal opinion.
For those retailers whose receipts are generated through a full POS system, I expect it's just a software patch that would do the job. The dedicated card terminals may need something more.
But even if it is a "hardware problem", why not give cashiers a jiffy marker to black out the digits? There's no reason to have them on the receipt since it is all settled electronically and the transaction code is enough to reconcile the day's accounts. As for me (at least in restaurants, where I'm asked to sign the slip and have the time to linger), I black out my card number myself.