The whole idea that someone can prohibit cities from building their own infrastructure is the thing I find most amazing every time I read about this topic. Should they also be prohibited from building their own roads?
In particular, as a user of cable, a private cable company cannot force you to accept and pay for its service. A government-operated cable service could.
From the perspective of a private cable company, government competition is unfair. The government does not have to use non-coercive means. It can force people to pay for its service even if they don't want to.
In the US, the best illustration of the danger of government enterprises is the public school system. Residents of an area are forced to support the local public schools, even if they send their children to private schools. The long-term loss of human potential of this system is monstrous. The economic waste is pretty bad too.
The best way to avoid disasters like the US public school system is to insist that transactions be voluntary. If you want to operate a cable company, fine, do it, but don't expect to be able to use coerced money to fund it or coercion to operate it.
The government is already involved, whether your bill says "AT&T" or "Chattanooga Municipal". The only question is whether data lines remain under the collective control of the people whose land they actually run under or whether that control is ceded by that government to a private corporation. The difference is who wags the government's tail, not whether that force is used.
A few years later a politician decides it will be politically popular to build a free road right next to your road, but will simply pay for it with tax dollars.
This is not exactly fair to you right? The politician has the power to take the money from constituants by threat of force (you go to jail for not paying taxes). You don't have this power.
In foresight of this situation, you get the state to sign an agreement that they will not compete with your highway with taxpayer dollars. They are welcome to build another toll road, but it just can't be subsidized by the tax payer.
So yes, there are cases where is makes sense for a government to prohibit itself from building a road.
Might feel that way, but I don't think citizens have a duty to be fair to businesses. Corporations exist to further the public good, if they don't do that, I have no reason to be fair to them.