It's carried to market, stored, arranged in bins, cooked, brought to the table, and eaten. The waste products are carried off, composted one way or another, and used to grow new food. The flow of material forms a circle of value, where each person in the chain has goods to pass on to another because he, in turn, has received goods from someone else. When we exchange money for a good or service, what we're really doing is exchanging work for work, or value for value. When I collect money for something I've given to or done for another, I'm collecting a symbol of the goods or services that other person owes me in return.
All money does is keep the exchange balanced.
One of the objections to mixing money and the Craft is that money corrupts the person who takes it. Many people who object to charging for teaching are perfectly willing to see a student give time and work in exchange for teaching. In saying that no one is to charge for the craft, you are necessarily saying that nothing is to be given in exchange for the craft, in any way, shape, or form. There is no balance which is expected or possible. This is appropriate for religions which consider the Divine to be separate from and not to be contaminated by contact with the mundane world.