There are two big obstacles: 1) Building a last-mile network is very expensive. There is a lot of backbone-style fiber in the ground but getting end customers

There are two big obstacles: 1) Building a last-mile network is very expensive. There is a lot of backbone-style fiber in the ground but getting end customers connected to that network is a complex maze of permits, digging, pole attachments, and so on. Just the manpower alone is staggering. Verizon spent years and billions on it and all they have to show for it now is a disgruntled former CEO and having fobbed off 2/3rds of their former wireline territories off onto Frontier and Fairpoint. 2) There is a lot of people-based inertia to overcome. As individuals, people object to having streets dug up, new equipment boxes planted in places, and all of the general dust and noise that construction of any kind creates. Plus your competitors will try to throw up roadblocks and, let's face it, they have more money and influence than you do. And if you want to do more than serve single-family houses and townhouses, you will have to negotiate with building owners for access. Even when the residents are the owners, like condominiums, there's still a process to gain access to walls. Then you have to consider how you get your wires from A to B; do you go above ground (easier but then you have to get access to the poles, which may be privately owned, and then you contend with the owners of the poles and the people who consider any new wires on poles to be unsightly) or do you bury (digging up streets, sidewalks, and utility easements has gotten a lot easier but you are still bound to disturb something and Woe Betide You if you accidentally hit a natural gas line)? And then, if you want to serve an "area" instead of "a city," what do you do when you need to cross city or county borders? Or a major highway (that's likely owned by the state government)? Not all cities are compact; take Dallas, it is both large and contains three separate municipalities inside of its general area. So, yeah, it's really hard and it gets harder the more people you have in a space, though the subscriber possibilities are much greater.