[esafak]

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

[michaelmrose]

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.