When you use key tags to get discounts at places like pharmacies and grocery store you will get targeted ads. Most of us have been selling our privacy for a bit of a discount since the mid 1970's. It's too late to put that genie back in the bottle. It just gets more obvious and more annoying when something happens that makes you a more attractive target for advertisers. For example, around the time my grandson was born I made a diaper run and started getting all sorts of baby oriented coupons and offers.
I seriously doubt that doctors anywhere in the world are participating in this sort of information sharing in any significant way.