That's for the publisher to decide. Your argument reminds me of the old chestnut "We're paying you in publicity!"

In your example the person is receiving something of tangible value and expecting to pay in near worthless coin.

In the circumstances the merchant would be expecting to receive a valuable service and simultaneously get paid for getting serviced.

More akin to Google paying to index you or going to a lady of the evening and holding your hand out for a tip after.