It has nothing to do with cost. All the TV app does is take all the content you can watch with the apps you have installed and puts it in one place. It's just an easy way of finding what you want to watch and the stuff you've already started watching without having to go app by app.
For instance, for me it shows my content from the iTunes Store, Amazon Prime Video, BBC iPlayer, ITV Hub and My5. When I want to watch something it goes straight to the content within the relevant app.
All due respect to /r/cordcutters, you don't need to go their for the basics you're looking for.
There are dozens and dozens of apps for major networks on Apple TV. For local, over-the-air (OTA) broadcasters, (NBC, ABC, CBS, etc.), they have ATV apps that don't require a PAID TV provider login from a streaming, cable, or satellite provider, so your options to see OTA networks is good.
As for other networks on cable, satellite, or streaming, you will need that paid provider login to stream through their apps on ATV. These are called 'TVAnywhere' apps and here is a list of what are supported on Apple TV...
https://support.apple.com/en-us/HT208083#usa
You might want to consider what networks you like most, find a cheap live streaming service like Sling TV, Hulu with Live TV, DirecTV Now, etc. to subscribe to and that will give you the TV provider login you need to watch the independent apps for those networks on your Apple TV.
Another advantage to an over-the-top (or OTT) service like those listed above...two of them - Playstation Vue and FuboTV - are fully integrated with listings and suggestions within the Apple <strong>TV app</strong> on fourth and fifth-generation Apple TV devices. Users can search and browse selected shows and launch directly to programming on those services. Be advised, the other OTT services are not (yet) compatible with the TV app.
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