Competition through the same laid cable? How does that make sense?
Not sure how energy companies (mains electricity/gas(-the-actual-gas-not-gasoline)) work in the US, but I can choose my 'energy provider' to whom I pay my bills[1] but it's the same national-grid pipes/cables coming into my home. As it can be with POTS, and the copper cables that go between me and the local exchange. FTTP
might have been laid by one of several providers, for high-speed internet, but it also might be ultimately managed/maintained or even laid by the equivalent to the National Grid but for phones and then you're again free to choose which company you pay for your landline/broadband...
I've not done much switching and changing, myself, and I don't know how many areas have High-Speed Internet only through a given supplier and you have to suffer 'inferior' ADSL (or are beyond even its reach, until the local village bands together to lay their own few miles of cable across a willing farmer's land) so leaving you with either truly awful connectivity (compared to most people's current expectations) or forcing you to invest in satellite-internet solutions just to take part in the modern world.
And I'm one of those that doesn't even switch energy-providers as often as I maybe should consider doing (like it's said that people are more likely to get divorced than to change their bank, even...), so I'm not even an expert on what
really happens in the UK. But separating the infrastructure from the 'provider' isn't really an unknown thing. (Ditto different train companies, running on the same tracks.)
But something tells me that the US attitude to federalised infrastructure (most, obviously not the given example of USPS acting as a backbone to the 'competitors') or even jurisdiction-by-jurisdiction caretaker bodies doesn't give that sort of flexibility. You get what you already got, or can pay extortionately to get, I must presume, but stand to be corrected.
[1] By whatever criteria. Perhaps just because they're the one currently not asking the most for the kinds of consumption I have. Perhaps because one company guarantees you pay for 'green' electricity.