The Library may share the same tab bar as the other buttons in the TV app but they are otherwise disconnected. It’s like having two separate apps rolled into one, each with their own UI components and each operating on a different set of data. It’s like having two people living in the same house that do not talk to each other. For the Library tab, Apple essentially took the old iOS Videos app and transposed it as one screen inside of TV.
They didn’t modernise it all, and its age shows through. The Library knows about content downloaded locally to your device, and your iTunes Store purchases, because that’s what Videos could do. Newer inventions like third-party TV Provider apps or Apple TV Channels subscriptions, which the Videos app did not incorporate because those components simply didn’t exist at the time, are therefore not shown at all. Library has no awareness of them. If you find something in Watch Now on a streaming service, you can’t add that to your library. You can only add it to a separate Up Next queue, which is only exposed as a single horizontally-scrolling list in the Watch Now tab and offers no further categorisation or filtering. Something that the Library tab would be perfect for, if it actually worked as you would naturally expect it to.
Box sets were handled badly in the Videos app, and that behaviour has been brought across wholesale into the TV app. Despite the other parts of the TV app having access to a full catalogue of TV shows, with information about their seasons and constituent episodes, the Library is siloed off from that data. It merely deals in files and file downloads. So, if you bought the first five seasons of Game of Thrones as an iTunes Store box set, Library sees that as a block of 50 video files, and it naively groups them together. The structured season metadata — that the TV app can show you if you were to look up Game of Thrones in the Search tab — is completely ignored. The TV storefront also rarely surfaces bundles like box sets for sale; users hunting the best deals have to continue to look in the iTunes Store app.
Whereas the Library tab is rendered as native table views, the other tabs are thinly-wrapped web views. Each time they reload, you see a full-screen spinner and have to wait. In fact, if you open the TV app whilst offline, the tab bar will vanish and you can only see the ‘Downloaded’ part of the Library. So, remember that Up Next queue which serves as your todo list of what to watch? You can’t actually see that if you are offline — even if you have downloaded the shows in advance. The design of screens varies dramatically between the tabs as well; both Library and Watch Now include navigation that shows a 2-column thumbnail grid of results. In the Library, each of these thumbnails is accompanied by a textual label that says the name of the show. But the Watch Now quasi-web environment omits these labels altogether (which makes quickly scanning search results annoying).
Everything is just very disjointed, both in concept and in their underlying implementations. A better TV app would have everything holistically driven by the same shared data source. You should be able to add any show to your library; it shouldn’t matter if that show is backed by a physical file on disk or not. The Apple Music app does a much better job at unifying the deprecated iTunes Store and the modern subscription-based experience. If everything in TV app was cohesively connected, it would also solve other complaints I have about the TV app for free. For instance, if I could add all the shows I am watching on Apple TV+ to my library, I wouldn’t be so annoyed that Watch Now is overwhelmingly featuring content that I don’t own and need to pay for. In this theoretical happy place, I could add all ‘my’ shows to the library and rarely need to look at the other tabs; many Apple Music users manage their songs in exactly this way. However, it isn’t possible with TV as the Library isn’t aware about anything apart from stuff purchased from iTunes.