The last mile is going to be a monopoly, whether it be water, sewer, cable, electricity, phone, or fiber.
It is? Why?
Look at data. Most people living in urban areas in the US have a choice of two "last mile" data providers: the phone company and the cable company. The fact that they use two different technologies is completely irrelevant in this day and age. You can get phone service from the cable company and internet service from the phone company. Now the phone company is laying fiber in many places which offers as much performance as cable, and they're certainly not restricting this to areas where the cable company doesn't have service!
You don't need people running cable to your house in case you might want it. You need people running cable to your house on demand, when you order the service. This clearly works, since it has been done. If you refute the idea, ensure that your refutation is compatible with the reality of the telephone/cable duopoly found in virtually every US city.