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Comment by organsnyder | Hacker News Reader

Given that they're probably already tracking everything via my credit card number (whether I sign up for anything or not), I don't feel like much privacy is being given up.

Though as a rule I don't bother with most of these programs, mainly due to the inconvenience factor.

I've lost hope of maintaining my privacy through any actions I can take individually. A legislative solution is required.

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Correct me if I'm wrong, but if you're using a credit card the bank is only getting a receipt that shows the sum total of the transaction and not an itemized receipt. The club cards are consuming and tracking the data of the entire transaction.

The club card acts as unique id to track you. The credit swiped at the machine has a unique id that they can use to track you.

The club card works across multiple credit cards and cash. That’s the main difference. And you might possibly track 2 people who control the household (wife gets one, husband gets one)

Using Apple Pay would circumvent the CC tracking because it only transmits a one-use number.

Unfortunately (from some perspectives), this isn’t true. Each instance of a card in Apple Pay has a long term Device Account Number (DAN) that functions the same as a physical card’s number (though there is no link between the DAN and actual card number from the merchant’s perspective). The same DAN is used across every transaction. The only way to get a new one (which is pretty easy, relatively speaking) is to unload the card from Apple Pay then re-enroll.

Was not aware, thanks for the clarification.

I've been wondering about returns lately using Google Pay consistently. It seems with returns they often ask 'do you have the card used for the purchase?', but with one-time numbers I don't know if the card will be recognized. My last several purchases I don't recognize the last 4 at all, and wouldn't be able to exclaim, 'yes, that's my card'

While returns are made more complicated by Google and Apple Pay, the card numbers aren’t single-use (which I’m not sure if you mean to imply is the case with google pay today). On both iOS and Android you can view the last few digits of the Device/Virtual Account Number.

I don’t have an Android device to test these instructions on but they seem plausible and corroborated: https://supportcentre.natwestinternational.com/Searchable/91...

When I made a return for an Apple Pay purchase at Target, they saw that the transaction was marked “Tapped” as card type and took my word for which card was correct. Who knows how long that’ll last. Where I really expect to run into problems down the line is when I try to take advantage of the insurance benefits offered by cards and can’t produce an invoice/receipt with the expected card number on it.

The receipt has the last four digits on the card. Localizing that specific card number to the store and you are going to get pretty complete profiles on people. There will obviously be some duplicates but some smart algorithms could match up the common purchases. If I always buy the same boxed tea and the same deli meat, patterns can arise. The guy who buys a 1/2lb of swiss and 1/2lb of roast beef every week is probably a different person than the one that buys 1lb of cheddar and 1lb of turkey each week. Associate my other purchases with my deli meat choices and they can track when I came in for some special dinner ingredients I've never bought and a box of my usual tea bags. Even purchases that look unremarkable at first glance, like bread, eggs, and milk, have trends (bread brand, egg size/brand, 1%/2%/whole/skim/brand of milk). Having the last four digits makes it a lot easier to track customers but even without that, there are probably unique customer trends you can pull out of the seemingly anonymous data. At minimum the store could print out some coupons that it thinks you would be interested based on your latest purchase and what other people buy with the things you buy. A mom buying capri-suns and lunch snacks would probably be interested in similar kid lunch items.

The store is able to build customer profiles using credit card numbers. The bank doesn't need to be involved at all.

Yes, it won't be perfect (especially if one uses multiple cards), but many stores are getting extremely sophisticated with their techniques for profiling customers.

The grocery store has access to your credit card number when you swipe it. It can associate that card (or a hash of it) with your itemized receipt.

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