> Well for one thing, at least in my experience, most credit card transaction data does not include granular information about the transaction (like the list of groceries you bought).

No, that information is collected as part of the "points" discount card and then sold to advertisers together with your credit card transation data.

You don’t have to give them the points card.

Also, I know an engineer that was inside a monstrous grocery chain many years back. Back then the payment and loyalty systems were separated by technical measures and firing level policies. If you used a CC without a points card they were not able to associate it to any kind of account.

Obviously the CC processor could but they didn’t get a list of purchases.

If you use the same credit card at walmart.com and in a physical Walmart store, then your itemized in-store purchases will show up as orders in your walmart.com account. This is without providing any other form of ID.

home depot is the same way, i bought something online on HD once and one day went in the store and bought something with the same credit card and the emailed me about my in store purchase.

i never logged it or provided any other information than my credit card swipe in the store but they tied it to the account i had on homedepot.com

But to what benefit? I use a discount card at my local supermarket. It also saves me anywhere from $0.10 - $0.40/gallon on gasoline. Beyond getting lower prices, I don't see any personalized marketing tied to my use of the card.

But the supermarkets gather that data, for sure. Several times I've bought a brand name item, then reverted to generic, then got offers related to that brand (just because I was buying based on value). I assume if they can establish a buying pattern with a few offers then often that will convert someone to the brand goods. (It's way easier just to pick the packet that looks like the one you got before than it is to look for the best offer).

One thing about returning to relative wealth is how much stress it removes from 'weekly' shopping.

I was ambiguous in my comment, but in my mind I was thinking about the loss of privacy from newer electronic transaction standards vs credit cards transactions. I suspect itemized data is generally not transmitted with the newer standards but I could be wrong.

I would like to know if this is still true.