Most regions are aware that cable and/or phone lines form a natural monopoly, and thus intentionally granted that monopoly, placing regulatory bodies just as they did power, water, etc.
Just look at how badly Google Fiber is failing some cities to see how hard it is for "another provider could come in and build lines and provide service". It may be "slightly" easier to have competing cable providers than competing power companies (though keep in mind early America did have more competing power companies in some regions), but it's not that much easier, it's still a natural monopoly.
This has always been called a "natural monopoly": https://en.wikipedia.org/wiki/Natural_monopoly
Most regions are aware that cable and/or phone lines form a natural monopoly, and thus intentionally granted that monopoly, placing regulatory bodies just as they did power, water, etc.
Just look at how badly Google Fiber is failing some cities to see how hard it is for "another provider could come in and build lines and provide service". It may be "slightly" easier to have competing cable providers than competing power companies (though keep in mind early America did have more competing power companies in some regions), but it's not that much easier, it's still a natural monopoly.