I got my parents a Roku a couple years ago. They finally cancelled cable, so I got them a few more Rokus for the rest of their TVs.
While setting them up, I noticed they didn't have to sign into quite a few of their apps, such as Hulu, Disney+, Peacock, and PlutoTV. The apps were already signed in and ready to go. Why is this, or how does that work? Is it some form of SSO where signing into the Roku with their Roku account will now automatically "authenticate" the other apps? Or did Roku keep track of their passwords? Is there a setting that controls this behavior somewhere?
(Not every app did this. Netflix and Freevee had to be manually signed into on every Roku.)