A community in Lancashire, England, has taken it upon themselves to dig, lay and build a complete 1 Gbps FTTH network. Members of the community have been able to buy shares to finance the project, and then they've mucked in to carry out all the leg-work themselves, with farmers digging trenches and other locals installing the technology. I find it very inspiring: especially given I live in London and still can't get FTTH. Business plan, videos and info on their website: http://b4rn.org.uk
EDIT: title changed from "...DIY Google Fiber project" to "...DIY 1Gbps fibre project"
Rural landowners have large tracts of land, and the land is in fewer hands. You need less individuals to buy-in, since a single buy-in on the project can mean miles of line.
You don't need a jackhammer to dig up sidewalks and streets, and you (presumably) don't need as many (if any) permits; you don't need to take as much care not to disrupt existing utilities, and you don't need to worry so much about noise and other regulations.