The term "monopoly" doesn't really make sense for a government, they don't operate in a commercial/economic space where 2 governments could compete with each other. Also luckily a lot of us live in democracies where you have at least some degree of control over what the government does.
(Edit: eh, I'm too tired, I guess you're arguing there is a monopoly on last-mile infrastructure then, which theoretically doesn't need to be a monopoly. Okay. In most cases it's a monopoly anyway because "over-building" existing last-mile connectivity won't be used by everyone and is thus less profitable.)
Your edit caught my meaning; I should have been more clear.
There's always less profit potential where there is more competition, which is one reason why people suggest that monopolies are capable of providing higher-quality products (and services).
Interestingly, some local governments are known (or at least have historically) to use their permitting powers to extract significant amounts of money from telecoms and others. I am not really sure what to do about this, but in the early days of power poles, few/no permits were required to use them, and there were many power providers sharing the same poles; it was messy, and contributed to unreliability, but it worked and allowed for competition.
(Edit: eh, I'm too tired, I guess you're arguing there is a monopoly on last-mile infrastructure then, which theoretically doesn't need to be a monopoly. Okay. In most cases it's a monopoly anyway because "over-building" existing last-mile connectivity won't be used by everyone and is thus less profitable.)