> To opt-out from our anonymization of your personal information to perform data analyses, please provide your Mastercard or Maestro payment card number below.

This sounds like they are going to continue using my purchase data but without anonymization? Not a native speaker so perhaps I'm just misunderstanding the sentence.

They don't charge 3%, they charge about a tenth of a percent (0.11%). What you think of as fees is actually a basket of charges going to different parties. almost 2% goes to your (the purchaser) credit card company to cover the risk of you not paying them, about a percent goes to the store's bank to cover the case when they have to give the money back (either because it was a fraudulent online transaction, or the store cheated the customer and the customer went to their card issuer, etc.) and that tiny little bit that's left goes to Visa/MasterCard.

Credit transaction fees actually make lots of sense and are grounded in the actual cost of the financial product. As a merchant, you can choose to accept only debit cards to avoid the cost

With VISA and MasterCard yes, but e.g. the German girocard network on its own doesn’t sell anything, and there it depends on your bank (and most banks don’t sell that data either).

So if you have the choice between using a girocard or a credit/debit card to buy a product, the credit/debit card is significantly more likely to sell all your data.

How can I opt out a virtual card number through Apple Pay? It doesn't seem that you can get the full "Device Account Number".

It used to be common to track the mac address of customers that pinged the in-store wifi. Not sure how much this happens now that some phones randomize mac addresses.

The accuracy by Bluetooth is horrendous.

Which chain?