> Classic liberal economics (from e.g. John Stuart Mill and on) generally acknowledges that natural monopolies exist and that it's generally beneficial for everyone if they are publicly owned.

The general problem here is that the "natural monopoly" tends to get drawn far too broadly.

For example, people call the telephone network a natural monopoly, which was Ma Bell's argument for making it a monopoly. But which part exactly is the "natural monopoly"? They were telling you what kind of telephone you could use (and requiring you to rent it from them), and tying not just local phone service but long distance service to the use of their last mile lines etc.

Even when they got broken up, the thing that kept the AT&T name was the (solitary, still a monopoly) long distance carrier, as if that was unquestionably still a natural monopoly. Then the internet came and proved otherwise. It turns out if you want to make a connection between New York and Los Angeles, it doesn't matter very much whether it's routed through Houston or Denver or Chicago, and if you have to you can even use a route that goes through Orlando and then Seattle. So transit is a competitive market and "long distance service is a natural monopoly" is BS.

The actual natural monopoly is the trench or utility pole on the road that carries the cable. At worst the cable itself, but installing the pole or digging the trench is way more expensive than adding another cable to an existing one (in the absence of some regulatory capture or inefficient incentives making it otherwise). And it's certainly not the things at either end of it. The other end of the cable that goes to your house should be at a local peering exchange where different companies compete to patch your cable into their equipment.

It's the same for electricity. The natural monopoly is last mile distribution, not generation or even really transmission.

And then if you give a private company a monopoly on something that isn't even a natural monopoly, of course the results are stupid. The thing that causes good results in markets is competition. So what you want in order is competitive market > local government monopoly > private monopoly. But you still don't want the second for any part of the system where you could have the first.