Regulars here know that most privacy laws are just window dressing around an active industry based on the trade of your personal information. Here is an accessible summary of one way that happens with respect to your prescription drug purchases.
It’s called ‘prescription match back’ and any computer science major will understand the algorithmic basis for it. Just choose the hash function on names in a way that matches how hashes of open data are computed, and just match ’em up. Gosh. Almost like it was arranged that way. Who’d have guessed?