Personally, I find it creepy as hell. I don't want McDonald's to know if I've ever eaten at McDonald's. Call me crazy, but I don't want every person with a profit motive in the world assembling a dossier on me that it uses and sells.

That being said, that's what they signed up for. What did they expect?

I think that getting discounts through loyalty programs should be illegal, because people aren't qualified to evaluate the value of the information that they're selling. If you want to do this, become a private club and simply don't sell at all to people who don't want to be tracked. Instead, it effectively becomes a transfer of cash from people who don't want to be tracked to the ignorant, and a transfer of the data of the ignorant to unscrupulous algorithms and data brokers.

It's not a coincidence that loyalty programs are mostly pushed in convenience store and drugstore chains, grocery stores of last resort for people who lack transportation and live far from a real grocery store.

> That they will charge you more if they know you will come back anyway?

That's certainly a concern. But that's a well known one that at least has some attention. But that McDonald's app knows your habits when it knows where, when, and how much you spend. Combined with 100 other sources of data about you, that might be the tipping point into a new way to exploit you. Hell, you mention that you started going to McDonald's more often and buying particular foods because your daughter is sick. Do you want that information going to insurance companies? How about to quack doctors selling miracle cures? What about PACs?

edit: that information could literally be used to deanonymize your comment.