It's a legal hurdle, not a technical one that prevents the 'above the board' software suppliers from adding this feature.

Pirates clearly are able to extract the 4K video and upload them to torrent sites, but the average media consumer would rather pay a netflix subscription fee that deal with the shady underworld of those sites with the virus installing and crypto mining popups, warning letters from your ISP, etc.

They've managed to make it hard enough that the number of people that do it is insignificant to their bottom line.