I suggest you read some of these agreements, they're usually online. Here's the one for my town: http://www.wilmingtonde.gov/docs/1320/3716Rev1.pdf. These aren't sweetheart deals. Generally, they extract millions of dollars for tangentially-related municipal programs, and then have build-out requirements forcing you to serve areas above a certain density even if you can't sign up enough customers to make it profitable. Basically, the terms are unattractive enough such that only the big de-facto monopolies are willing to take the deal.