Actually, pole dry beans would be a small niche crop. Bush beans are machine harvested like wheat or barley. http://www.agmrc.org/commodities__products/grains__oilseeds/dry-edible-bean-profile http://www.ers.usda.gov/topics/crops/vegetables-pulses/dry-beans.aspx Even green beans mass production is bush types machine harvested. There are no harvesters for pole beans so even as green beans they are a labor intensive crop and labor is expensive. Even so there is some commercial production of pole snap beans. http://content.ces.ncsu.edu/pole-bean-production/ http://extension.uga.edu/publications/detail.cfm?number=B1369

I've read (I think in one of Rancho Gordo's books) that they don't trellis their pole types, but let them sprawl over the ground, and when everything's dry they just mow up the lot and throw it in the shucker, same as for bush beans.

That is like growing vining pumpkins....

"they don't trellis their pole types, but let them sprawl over the ground, and when everything's dry they just mow up the lot and throw it in the shucker, same as for bush beans."

I suppose that works for them because they're in a dry climate. In my climate that would be a wild orgy of mold, disease, and insects.