There are additional privacy layers in the system, such that every time you make a purchase, a temporary card number is generated and used, rather than your act

There are additional privacy layers in the system, such that every time you make a purchase, a temporary card number is generated and used, rather than your actual card number. This is beneficial as it prevents the retailer from tracking your purchases, but requires interactive participation from the bank, which needs to map that number to your actual card number in real time. As part of the onboarding process when you enroll a card, your bank must confirm the enrollment to ensure this process can take place. It seems to be part of a multi-step key exchange mechanism [0] mediated by Apple but stored locally at either end, ensuring that Apple does not retain your card details at any step of the process. Of course, without bank participation, there aren't two parties to actually mediate between. [0]: https://support.apple.com/en-us/HT203027 https://support.apple.com/en-us/HT203027