That the last-mile costs are so extreme that utilities must be monopolies is not obvious either. We've built out the last mile in the U.S. many times over for many things, and where we've allowed it (as opposed to preempting it a priori) we've had competition (e.g., cable). Even where we don't have direct competition, we do have indirect competition where consumers can vote with their feet (e.g., power rates vary regionally).
Obvious or not, at the time the monopolies were granted, that was the assessment.
And yes, in dense areas, we may have two cable competitors who've both built out the Last Mile. But it is not everywhere, and there are many areas where there is zero build-out, and the only service you can get is DSL on old copper maintained by the TelCos.
Moreover, the monopoly system for Electrical and TelCos was adopted requiring them to provide service to ALL, both the highly profitable dense urban neighborhoods and the massively unprofitable rural areas with one farm every several miles. See the Rural Electrification Act of 1936.
The fact that it was done this way pushed the US very far ahead in the world, providing both electrical and telephone service almost everywhere.
The fact that the Internet was NOT done this way puts us somewhere out the top 25 in Internet service.
Central planning will create a disaster when completely relied upon, but completely avoiding it will also create a disaster. Some things work as a system and society with a measure of applied foresight.
My local utility charges users $5,000 per installed pole for last mile connection. I've priced poles and wire, they are turning a hefty profit for last mile connections.
How many people does it take, and how much equipment? If they're using contractors and have to, say, hire a crane, things can add up pretty fast.
That doesn't mean that they're not necessarily price gouging or making a profit, but often things like poles and wire are a small part of the actual cost of installing infrastructure.
