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.
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.