system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do businesses such as grocery stores have cheaper prices for "members" when membership is free? How do they benefit from that?

Most retail locations have a membership program that is free, giving them access to cheaper prices. How does the store gain from that? It seems like all they're getting is my phone number and e-mail address.
gpt
Customer Loyalty programs ensure that customers keep coming back to your store.  It's like a sandwich shop that has a "buy 10 get 1 free" deal.

These days, it also helps them collect data about who is purchasing what.  Getting your phone number gives them a single unique identifier so they track your purchases and get better information about what people are buying.

Beyond that, grocery stores used to offer sales *all the time* without a rewards/loyalty number.  These days, they just require a membership to get the sales they used to have *without them*.  It's not costing them anything extra.