I just checked, iPad has it (and using colour coding, as that has come up elsewhere in these threads). On Apple TV a subtitle menu appears in the time bar, but it doesn't seem to do anything in either the "Automatic" or "CC" options it gives?
CC is a bit of an Americanism, perhaps it is running more directly though some Apple playback code that is more particular about subtitle formats?
I suspect the ultimate case is probably low usage statistics not making it a priority. The icon / BBC logo didn't update at the same time as the iOS version, so I suspect its a separate codebase for some reason?
iPlayer on TV (across all platforms) is a generic web application, topped with a custom wrapper app (think webview) for each platform, responsible to hook platform’s native APIs to Web/JS APIs.
I’m guessing there are some complications hooking Apple TV’s native subtitles APIs to relevant web APIs, and low usage statistics doesn’t help prioritising fixing the issue. Although the rumour is that they are working on a completely new Apple TV app.
I think Apple must allow it, either that or Google have tried really hard to capture in native code the "shitty non-native web app" feel with the YouTube app. But the iPlayer app does feel fairly native.
CC is a bit of an Americanism, perhaps it is running more directly though some Apple playback code that is more particular about subtitle formats?
I suspect the ultimate case is probably low usage statistics not making it a priority. The icon / BBC logo didn't update at the same time as the iOS version, so I suspect its a separate codebase for some reason?