TechCrunch’s Romain Dillet reports that the “single sign-on” feature of tvOS 10 didn’t make the cut for the initial release:
And yet, one of the most interesting features is missing from today’s update – single sign-on. At WWDC, Apple promised a new feature that would make it much easier to sign into apps. With single sign-on, your cable subscription credentials will automatically sign you into Apple TV apps so you don’t have to type your password over and over again. Single sign-on didn’t make it in time for tvOS 10 and should be available later.
That’s a bummer as for me personally it was the most anticipated feature of the update, but it does explain why I couldn’t find any trace of it in the tvOS beta. According to TechCrunch, Apple is promising the feature for “later this fall”, though one would think Apple would want to implement it before the fall TV season gets underway for real.