Telephone and data is an interesting one. It's an area that on its face is a natural monopoly, but in much of the US we ended up with two telecom providers
Telephone was a monopoly because it doesn't make sense to have more than one company string a wire to every house and business. But, all that wire could carry until the 90s was a voice call
Likewise, in the 60s/70s/80s cable TV became a thing but it didn't make sense to have more than one TV wire to every house, because it already has all the TV you can get, and at the time all it could carry was video channels
In the 90s these networks converged: when everything is digital, a network carrying digital signals can carry any kind of data
So, in urbanized and suburban areas we largely have a competitive market in what would otherwise be a natural monopoly. The problem is, because it's competitive in like 80-90% of the country everyone's been relieved of their universal service obligations (which applied only to voice service anyway) so there's been little incentive to expand into more rural and underserved areas
Telephone was a monopoly because it doesn't make sense to have more than one company string a wire to every house and business. But, all that wire could carry until the 90s was a voice call
Likewise, in the 60s/70s/80s cable TV became a thing but it didn't make sense to have more than one TV wire to every house, because it already has all the TV you can get, and at the time all it could carry was video channels
In the 90s these networks converged: when everything is digital, a network carrying digital signals can carry any kind of data
So, in urbanized and suburban areas we largely have a competitive market in what would otherwise be a natural monopoly. The problem is, because it's competitive in like 80-90% of the country everyone's been relieved of their universal service obligations (which applied only to voice service anyway) so there's been little incentive to expand into more rural and underserved areas