That's exactly the problem I'm addressing: the lack of competition. But competition is vital to a free market. There has to be competition. If it's a natural monopoly, it needs to be in the hands of the community, the government, or at least very tightly regulated.
But competition is possible. I have a choice of many broadband options. It used to be (20 years ago) that cable and phone where the only options to get internet, but now both the phone company and the cable company have fiber networks, and there's a community fiber network that's accessible to many ISPs. Companies that own their own last mile may be required (or are incentivised) to allow other providers to use it.
Of course if only one company owns the last mile, then that company needs to be tightly regulated, government controlled, or required to share. But with the switch from phone or cable to fiber, everybody needs new infrastructure, and everybody needs to lay new cable. That also evens the playing field a bit.
It's bizarre to see the free market fail so hard in a supposedly strongly pro-free market country like the US.