How can it be that in 2020, I am unable to watch HD catch up services from ITV, Channel 4 or Channel 5 through BT youview box? The picture quality is quite frankly an embarrassment.
They are SD definition only. BBC iplayer is HD also Britbox is full HD but the latter is a subscription on-demand
Because those broadcasters either have an exclusive carriage agreement or want to sell you a premium subscription to access HD content
It is simply a decision from the supplier of the players ie ITV , C4 or C5 respectively not to provide HD content. BBC Iplayer , BT Player have provided HD for many years ( and indeed some 4K content) as of course the Netflix and Prime Video Players do. Even Now Tv eventually introduced HD content for some of its ondemand content.
@jam2000 they do but not on Youview or BT TV as neither have a carriage agreement for the HD content. Due to licensing agreements Channel 4 can make HD available for free on handheld devices but set top boxes are locked out because they sell access via commercial agreements