Standard Oil, US Steel, AT&T are the best known examples in the US. None of these (including AT&T) were government granted. They also share a few key traits
1) They dominated their "primary" markets
2) Their primary market was deep, and competing with them was cost prohibitive for any economic entity as in lose the GDP of a small country expensive.
Ok, I can’t talk about the first two because, frankly, it’s been a while.
But AT&T - you kidding me?! It was illegal to even bring your own phone device to their network! It was a classical example of government protected monopoly.
A free market will break its own monopolies. A market corrupted by government regulation will need government intervention.
With regards to it being illegal to connect to the phone system with your own device... this was a notion pushed by AT&T's legal, and operations teams.
https://en.wikipedia.org/wiki/Carterfone has some useful context on the regulatory decisions which compelled AT&T to allow third party devices on "their" network.
Ultimately large monopolies contort the institutions, governments, and legal systems they are surrounded by. You wouldn't believe that a Trillion dollar corporation would argue for legislation that wasn't in their favor.
Yeah, but it is the legislation that is preventing the competition and thus making them a monopoly, otherwise they would be disrupted by nimbler, faster startups of the day for which a monopolized market is an irresistible target (little competition and large profits).
