No industry started out as a monopoly in America. A city might have service from a half dozen railroads serving a half dozen separate stations with no means of transferring between them. A half dozen electric companies would put up separate poles and lines along a street to serve their customers. If you go back far enough you find competing private fire companies so intent on beating the others to get the fees for putting out a fire that they would each sabotage the rest en route and let the building burn.
This was madness. States began chartering companies to provide certain services, from running turnpikes to building canals to supplying water, with exclusivity built into the charter. Later, cities found the corruption so overwhelming that - sometimes to try to guarantee some semblance of efficient service, sometimes to bring the corruption in house - they established their own departments: police, fire, water, sewer, streetcars, electricity, gas, and others. Others, like telephone and telegraph services and later cable and mobile phones, were given franchises that guaranteed them a set return although they had to provide service to everyone who wanted it regardless of the cost to do so. Only a few monopolies were created at the federal level, mail service, radio and television most prominently. As said above, all monopolies exist under regulation, either from the state’s Public Utilities Commission or equivalent or a Federal Independent Agency, like the FCC. Theoretically, the regulators ensure that the monopolies get back just enough in profit to keep the companies going. The pay scale for executives at a utility company, for example, runs a tiny fraction of those in the private sector. And competition, once the monopoly has been opened up as also true in much of the utility industry, shows that the imagined savings from opening an industry to competition is often illusory.
The same problems exist today as they did when monopolies were formed in the 1900s. It simply makes no sense for multitudes of cable companies to run lines to the various homes on a street. That’s duplicating all the costs with only the hope of a fraction of the return. Dividing a city in separate areas makes much more sense. Dividing electric generation makes sense only if every firm can use the same lines for delivery. That’s been a pattern now in many states. The commonality is always about delivery of service, not about size or type of service. Giving customers one integrated system is the ideal. Whether the government runs that system, charters the systems, franchises the system, or regulates private firms doing the system will vary with local particulars, since there is no one way that is the right way. Often there are many ways that are the wrong way, though. When that happens monopolies don’t look so bad.