Supermarket analogy (Score 1)

I can't understand what's different between what Google is doing and what supermarkets regularly do. At the supermarket checkout, they have these little coupon printers which spit out a coupon or two based on your purchases. Invariably, whenever I buy Tropicana orange juice, the coupon printer hands me a coupon for Minute Maid. There's obviously some database attached to these coupon printers with an entry for a Minute Maid coupon attached to the (trademarked) product name "Tropicana". Should Tropicana go and sue Coca-Cola (Minute Maid's owner) for infringement? Certainly not -- they'd be laughed out of court.