Mastercard sells your swipe twice. Once to move your money, again as data.

Mastercard doesn't lend you money or hold your account. It runs the wires between your bank and the store, and earns a small fee for moving the payment. That fee is the business everyone knows about. It is not the only one.

2 panels compared. Your swipe, sold once: ~2% of the sale; Charged to the store; The fee everyone knows — Your swipe, sold again (emphasized): Where, when, how much; Anonymized + pooled; Sold to banks, retailers, cities; $0 to you.

Every swipe leaves a trail: where you bought, when, how much. Mastercard strips your name off it, pools billions of these traces, and sells the patterns. Banks buy fraud signals. Retailers buy benchmarks against rivals. Cities buy spending trends by neighborhood. This is its Value-Added Services arm, and it now pulls in billions a year.

The same swipe gets sold twice. Once as a fee to move your money. Again as a data point in a report you will never see. You generated the second product, and you were never paid for it.

When the service is free or cheap, look for the second product. Often, it's you.