I'm a little confused by the following question and answer provided by MRU:
Fruit farmers pay beekeepers for their honeybees’ pollination services. Honeybees provide an external benefit to fruit farmers. However, fruits provide an external benefit to the beekeepers because their honeybees need fruits. Which external benefit is larger: honeybees’ external benefit to fruit farmers and fruits’ external benefit to beekeepers?
Honeybees’ external benefit to fruit farmers is larger
This seems like the least fitting answer to me. The fruit farmers pay the beekeepers for their services, so the benefits they get from this relationship are mostly accounted for by the cost. However, beekeepers don't have to pay the farmers for the benefit their bees get from pollinating their plants, so this benefit is an external benefit that farmers give to beekeepers. Am I misunderstanding something here?