It's not that customers don't want the retailer to know...
It's not that customers don't want the retailer to know them. It's that they don't want (to give personal details) to the cashier, who they think might do something with the information.
It's not that customers don't want the retailer to know them. It's that they don't want (to give personal details) to the cashier, who they think might do something with the information.