This is the issue. There isn't a free market in this (or many) sectors because of regulatory capture. If that were gone, if competition was even possible, then we would see improvement.
Physical networks like this also clutter up the skies or create areas you can't dig in, and accrue damage while decreasing in value each year until they are abandoned or upgraded.
Abandoned Telecom infrastructure is a serious issue all its own as well, no one wants legacy unused cabling running under their streets or in their building.
Just a point of clarification, the free market generally means independence from government regulation. This isn't the free market failing so much as incumbents using the power of government to force their advantage, part of the argument of the free market is that by not allowing the government to interfere in this manner no one can get laws written to benefit them because the government doesn't get involved in the first place. Now granted that's in a frictionless airless world with spherical cows. But to say the free market failed and the very next sentence say it is because of regulation from the government is oxymoronic.
So either way, monopoly is the inevitable end point.
And by monopoly, I am also referring to systems where there are a few big players that just don't compete against one another, or one where there is a big player and a few small but inconsequential players. All of these result in the same effect as plain monopoly.
The rare times you see overbuilding there is always a scheme involved, whether it's Comcast's recent edge outs to appear as though they aren't bleeding internet customers, or government money incentivising an overbuild cause the current ISP didn't document that they serve a set of addresses.
Capitalism isn't the absence of government regulations, you seem to have confused it with anarchism.
Capitalism is the name applied by critiics to a real world economic system existing at the time it was described based on particular structures of properry rights and the resulting class system. Government regulations systematically benefitting the dominant class is... very much one of the features widely observed to result from that system.
As it stands, competition found away around the wired line regulations. The wireless devices came along. And soon the satellite networks will give the cellphone carriers a real kick in the pants.