You’re conflating the individual practice of having a pessimistic threat model with a corporation’s entitlement to behave badly.
Of course I assume the worst from Walmart or any other public network — I just think they should have some class and provide a public good to their customers without creepy privacy invasion. Somehow they manage to provide free water in fountains without requiring me to scan my driver’s license.
If they published a white paper explaining the Differential Privacy properties of their customer analysis tech, I might revise my opinion.