It isn't cost effective to run fiber in rural areas. I live in the "suburb" of a rural town and my street has ~10 houses per mile. Head another mile down the road and the population density drops.
As a result, calling this "indiffferent" is just nuts when compared to areas that are currently served by dial up or satellite. I had satellite internet and while I got DSL-like bandwidth on large file downloads, the latency (1-3 seconds) rendered it barely faster than dial-up for general usage. I finally got DSL when lightning toasted the area's switch and the replacement had just enough signal to get me 768Kb.
Depending on collision avoidance, channel splitting, and the over-subscription factor, each tower could offer DSL-like performance to a couple hundred subscribers. Assuming each subscriber is a family/business, that serves a few thousand people. The tower is likely half the up front cost and less than 10% the long-term maintenance cost of fiber.