Heard at the grocery store: "You only bought 1 apple so we're charging you for the price of two because of gas prices." It's a cost that can't be quantified to

Heard at the grocery store: "You only bought 1 apple so we're charging you for the price of two because of gas prices." It's a cost that can't be quantified to the customer. Why not just jack the monthly cost instead of tacking on a ghost charge?