Glenn Reynolds has been tracking worried comments by Susanna Cornett and Kim du Toit about the privacy hazards of supermarket discount cards.
However, sometimes hi-tech problems have low-tech solutions. My friend Ken teaches information technology for MBA‘s, and in his security classes he shows them a stupidly simple way to avoid nearly all the privacy risks of supermarket discount cards: He swaps cards with his students and encourages them to swap with each other. Everyone still gets the discount at the register, but the data is meaningless. He’s been using other people’s cards for years.