In the overall history, the 3rd rail telecom system is relatively recent. Before that, subway-el systems had telephone call boxes along the tracks in case a train broke down and had to report in. Also, stations, dispatchers, and shops had to have phones, too. Early on (1920s) transit systems had sophisticated large telephone networks. In the 1960s, one would often see an old style Automatic Electric phone on someone's desk for the internal system next to Bell phone for external purposes.
The Bell System was called a monopoly, but I think if internal private telephone and intercom systems were counted, as many large organizations had, the market share would be more distributed than people realized. Bell used to urge its employees (in company newsletters) to sell Bell service as superior to the private system. They'd show a picture of the dual phones on the desk to illustrate the point.
Note that in old movies the boss often had an intercom box on his desk, later on that service was integrated as part of the telephone key system (the LOCAL/ICM button). When was the last time we saw a separate intercom box on someone's desk?
Streetcars had "headway recorders". This was a contact on the overhead wire that registered each time a trolley went by and sent a signal to HQ. If no signal was received after a certain interval the dispatchers were alerted and sent out a repair truck.
That is one of the pitfalls of transfering ownership between the public and private side. It works in both ways. Privitization of public works is no better.
I must respectfully disagree with you about Mr. Insull. I'm not an expert, but I've read that while charged, he was found not guilty of all charges.(Wikipedia, FWIW, also says this).
What Insull did wrong was build up a highly leveraged entity that was vulnerable to the massive economic downturn of the great depression. Everyone cut back on power consumption and transport riding, so all of his interrelated companies got hurt and went bankrupt. (Most other businesses in the Depression either went bankrupt or came close to it. The Bell System chose to keep paying out its dividend even though it was losing money, and had to lay off a great many people. I believe Western Electric was decimated at the time.)
The Federal Government, through Ickes, at the time had a grudge against privately owned public utilities, and went after Insull and other companies. Many power companies also owned streetcar systems but they were forced to divest, losing some economies of scale. The people in FDR's administration weren't very fond of entrapreneurs as a matter of principle. In the 1920s the business community knowingly did bad stuff, but certainly not all business people were bad.
Unlike modern day crooks, Insull did NOT "pocket" his investors' money. He used it to build modern transport and power networks which worked very well. He left his empire in far, far superior physical condition than when he found them. His three interurbans, North Shore, South Shore, and CA&E were some of the best in the entire country, with high speed trains and superb service. The South Shore continues to run to this day. The North Shore and CA&E continued to run much longer than other interurbans, thanks in part to the infrastructure Insull built. The parent company may have been bankrupt, but the trains kept running. Most other interurbans shut down in the depression.
By building an integrated company, Insull was able to take advantage of economies of scale and built large generating stations and networks. These were more efficient.
The physical plant Insull built was of critical value during WW II. An incredible number of servicemen and materiel were moved on it (the North Shore served a key naval base).
There was recently an article in the NYT about Avis, saying it's been bought and sold many times, generating huge fees for intermediaries, but adding nothing to the business itself. As mentioned, yes Insull was a 'player', but he built real things and provided real services to the public.
Krambles was always highly respected in the transit industry. I believe he had done well after leaving CTA, perhaps running Pittsburgh's system.