Your grocery store knows more about your household than your doctor does.
That sounds dramatic. It is arithmetic.
If you have used a loyalty card for a few years, the store has a record of every item you bought, when, how often, in what combination, and what you stopped buying.
From that it can infer a great deal. Household size. Whether there are children. Whether somebody is managing a health condition. When your routine changed. Whether money got tighter.
None of that requires anything exotic. It is straightforward pattern recognition across a long record.
Regional grocery chains, including one in St. Louis, have been building recommendation systems on top of exactly that data.
The press releases describe it as personalization and convenience.
That is true and it is not the whole picture, and the difference is worth several hundred dollars a year to you.