Your speaking of places so rural that they do not have cable? If so, I agree. I think this is why Dish/DirectTV don't really compete with Cable. Captive audience.
On the other hand, companies like Comcast will exploit their captive audiences, and at the same time have competitive prices where the customer has options... -- dnoyeB "Then said I, Wisdom [is] better than strength: nevertheless the poor man's wisdom [is] despised, and his words are not heard. " Ecclesiastes 9:16
One needs to look at the technical merits of DOCSIS and ADSL They have very different trade-offs.
Then one needs to look at the business practices of the respective ISPs to make sure they are able to deliver on the technology. Is their internal network and peering is up to the task? It does no good to have a blazing fast first-mile connection if ISP limitations prevent you from utilizing it.