There are thousands of cases in which the seller trusts the buyer. Having worked 40 hours, I trust that George Mason University, my employer, will pay me. People place an order with their stockbroker to purchase 100 shares of AT&T stock, and the stockbroker trusts that he'll be paid. Companies purchase 5 tons of aluminum with payment due 30 days later.
Examples of honesty and trust abound, but imagine the cost and inconvenience if we couldn't trust anyone. We would have to lug around measuring instruments to make sure that it was in fact 10 gallons of gas and 1 pound of steak that we purchased. Imagine the hassle of having to count out the number of pills in a bottle. If we couldn't trust, we'd have to bear the costly burden of writing contracts instead of relying on a buyer's or a seller's word. We'd have to bear the monitoring costs to ensure compliance in the simplest of transactions. It's safe to say that whatever undermines honesty and trust raises the costs of transactions, reduces the value of exchange and makes us poorer.
Honesty and trust come into play in ways that few of us even contemplate. In my neighborhood, workers for FedEx, UPS and other delivery companies routinely leave packages that contain valuable merchandise on the doorstep if no one answers the door. The local supermarket leaves plants, fertilizer and other home and garden items outdoors overnight unattended. What's more, the supermarket displays loads of merchandise at entryways and exits. In neighborhoods where there's less honesty, deliverymen's leaving merchandise on doorsteps and stores leaving merchandise outdoors unattended or at entryways and exits would be equivalent to economic suicide.