Presumably that data would include time, amount, and vendor... but not item-level details. Right?

There's something else going on here.

Drugs often cost a very specific amount of money (When I buy drugs it's always something like 4.86e or whatever, not neat 4.99) so I assume it's easy to de-anonymize

> neat 4.99

i get what you are saying, but calling a price ending in .99 "neat" feels very wrong

It's in level 3 data.

https://www08.wellsfargomedia.com/assets/pdf/small-business/...

“For Level III data, only Mastercard® and Visa® corporate, purchasing, and fleet cards can qualify.”

So consumer credit cards can’t get this.

I'm not an expert on this, but I suspect merchants supporting level 3 data send it to the processor for all transactions, not just for corporate cards (if they even know it's a corporate card), but they only get the fee discount if it's a corporate card. Your credit card statement might not expose the data (or even get it), but the network can still sell it.