So, they had to have access to the backbone somehow. Is this possible for an individual rural location? Or even a small community in the U.S.? Do backbone providers have to give you access? Are the rates at all reasonable?
Backbone providers don't have to give you access, but they will sell to you, provided there is a way to connect you.
Backbone providers sell you IP transit, which is a very competitive market in well connected locations. The problem is to get to those well connected locations. You often pay far more (like 10x) for the transport to that location than for the actual IP transit.