AT&T's monopoly was definitely government-granted: there was even a law forbidding users to install their own 3rd party telephone receiver "to protect the AT&T

AT&T's monopoly was definitely government-granted: there was even a law forbidding users to install their own 3rd party telephone receiver "to protect the AT&T network"! I am not familiar with the other 2 cases but I wouldn't be surprised if it was, again, government-granted or not an actual monopoly. Think about it, it's logical: why wouldn't competing startups attack a monopolized market? It's ripe for disruption, after all. Monopolies can arise on the free market but unfettered competition will always defeat them.