He does have cost, the care and feeding of his animals, vets are not cheap. And sooner or later the cost of replacements and training.
Draft animals cut the costs of farming a lot, The question is can the draft farmer put in the time to plow as many acres as the tractor guy? That is up to the work ethic of the farmer and the price of fuel/weed killer.
I looked it up a team of large mature oxen sells for about $5,000.00, dang.