[craighay1]

It was unclear from the article whether this applies to only credit card transactions or also Mastercard debit cards. At least it is possible to choose not to use credit cards, a bit harder with debit.

I'd love to see how this data is "anonymised".

On a related note, in the UK at least, all of the big supermarkets have switched their loyalty card (data harvesting schemes) from offering "points" per unit spend to offering direct large discounts on certain items in store. Makes it much more difficult to justify opting out of giving away the details of your personal shopping habits to these corporations.