These are cases where it only makes sense to build one system, and any such system should be under public control, not under private monopoly control by some rent-extracting shareholder outfit.

Sure and they have done in the past. The existing networks weren't initially built by governments, they were built by private entrepreneurs and then nationalized. That's true at least for power and internet, admittedly I don't know for water piping, that might be old enough to pre-date private companies of any significant size.

Now should they is a different question to will they. In many cases it's OK to allow that. I think the US still has private railway lines. In other places there aren't any left. But I agree that for networks that require enormous amounts of land and where there's ~no scope for innovation, government monopolies can be beneficial. Water, power and roads seem clear cut. Rail is a sort of interesting middle ground where countries go back and forth because there is actually scope for innovation in how the signalling works and governments are typically extremely slow to deploy improvements.

This is simply not true in many cases, and the Rural Electrification program is Exhibit A, isn't it? Exhibit B is the national freeway system. The takeover of the government-built Hetch Hetchey to CA power grid by PG&E is exhibit C, granted a complicated story:

https://www.dailyjournal.com/articles/293699-a-hundred-years...

Certainly the private sector has a role to play, i.e. the production of water pipe itself is a competitive business, so is the production of fiber optic cable, and of tools and equipment - but the systems themselves should never be privately owned.

https://en.wikipedia.org/wiki/Turnpike_trust

(well, semi-private at least, corporations didn't exist in the same way that far back)

And the internet was all private and still is, with no change on the horizon.