And Pay by plastic the company providing the Payment gets a full list of everything you have bought and what each item costs to justify the finial price of the sale and Money transfer.
As a result the Banks sell those lists onto whom ever wants them The Supermarket also keeps lists like that but they are not linked to the Customer as much as the store what it sells and what it need to order. Though this is currently changing and the shops are becoming more and more involved in tracking individuals Purchases so that they can push advertising to them on things that they may want to buy.
The Banks on the other hand have a full list of your purchases so when they have a startup they can sell them lists of potential customers for their products in specific areas. Didn't you ever wonder while some areas where targeted with Mass Mail Outs of Sample Product and other areas where not?
Of course this is taken several steps further and the companies can now target individuals and hopefully increase their Market share at the expense of their competition.
Only times that this doesn't happen is when the industry is controlled and has to comply with Laws most companies do not have this restriction and make as much as they possibly can out of every sale that they make including the ones that get returned and the Fraudulent ones where they cover the costs in that sale not the banks who issue the cards.
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