The only true monopolies are those backed by the government, which the original AT&T was. There has never been a "monopoly" not backed by the government that did not benefit the customer. Standard Oil and U.S. Steel, the classic examples always used, both drove down prices and increased supply for the market. By the time the government took action both had lost significant market share already as competition improved.
The only ones on your list that create problems would be Comcast and Verizon (assuming not wireless) as they are granted local monopolies by local municipalities and governments through right of way access to utility poles, etc. Breaking up the others, as you are suggesting, would only harm consumers.
This is completely incorrect. Every unregulated monopoly catastrophically chokes an economy over time and those that are regulated are almost as disastrous.
Your own example, Bell System, is an example of an sub-optimal but obviously adequate regulated monopoly that worked moderately well over a century.
And US Steel certainly did _not_ have competition when anti-trust was brought against it. By 1907 there were no longer any competitors and anti-trust attempts only started in 1911.
What you do have today, for adopting pro-monopoly policies for decades is, among other things, the highest bandwidth prices in the developed world. Higher even than the comically inept regulated monopoly Telefonica. Which btw has phone plans and per minute charges a fraction of the US and where the idea for charging for an incoming call is unthinkable. And a food supply monopolies that inflates the price of food to stunning levels. The list is endless but my typing patience is not. So here's a link.
Your own example, Bell System, is an example of an sub-optimal but obviously adequate regulated monopoly that worked moderately well over a century.
Ummmmm, no.
Whatever your economic viewpoint, there's no credible way you can claim that the Bell monopoly was healthy for the economy. This is the same organization that had to be taken to court to allow new devices to be plugged in. Remember these? https://en.wikipedia.org/wiki/Acoustic_coupler They weren't built because it's more efficient for computers to communicate over soundwaves.
there's no credible way you can claim that the Bell monopoly was healthy for the economy.
The Bell monopoly invented the transistor. I think there's a credible claim that could be made that the invention of the transistor was healthy for the economy.
I did not say Ma Bell was good for the economy. And certainly not that it should have remained intact. I point out that had it been an unregulated monopoly, it have been worse.
The only ones on your list that create problems would be Comcast and Verizon (assuming not wireless) as they are granted local monopolies by local municipalities and governments through right of way access to utility poles, etc. Breaking up the others, as you are suggesting, would only harm consumers.