Because there's certainly skill involved in the successful managing of a stall. It's not that anyone could buy from the grocery store and sell at the stall and

Because there's certainly skill involved in the successful managing of a stall. It's not that anyone could buy from the grocery store and sell at the stall and make a profit; just the people who successfully make profit on a small farm. The suggestion is that the customer knowledge/access is what is providing value, not the farming.