Quote 1:
"[Q]: Why must I sign in to a BBC account to use BBC iPlayer?
[A]: Without signing in, you won't be able to play programmes or choose to benefit from the personalised features that BBC iPlayer offers including adding programmes for later, getting personalised recommendations, and picking up where you left off across your devices.
We need to understand more about what people are watching to ensure we are providing something for everyone. Up until now we could only tell how many people used BBC iPlayer, but having more data like age, gender and location will ensure we’re better serving all our audience. We share some of your personal information with TV Licensing to check if you are using BBC iPlayer and to keep their database up to date."
Source:
https://www.bbc.co.uk/iplayer/help/questions/signing-in/account-signin
Quote 2:
"[Q]: Why do I have to sign in to use the All 4 app?
[A]: To help us to find you shows you’ll love, we need you to sign in to All 4.
You’ll be able to pick up where you left off on any of your devices, add to a watch list and get recommendations suited to your tastes.
This simple sign-in will also ensure that all members of your household are watching shows suitable for their age.
We promise not to spam you with cute cat pics... but we will provide an All 4 just for you."
Source:
https://www.channel4.com/4viewers/faqs/category/36/nature_of_issue/411/nature_of_issue/436/device_used/336