You or I would gather up all that fallen leaf, brush it off, and color-cure it. Then we would grumble, and stalk-harvest the rest. We would end up with a fair quantity of quite useable leaf.
For a commercial-scale grow, there is no profitable way to do that. Since the profit margin for commercial tobacco growers is slim, even with mechanization, that photo of leaf on the ground, and tattered leaf remaining on the standing stalks represents a financial catastrophe—a loss of massive investment, as well as scant annual income.
Bob