1080p WEB-DLs are very common if you're in the right places, but even public trackers should have plenty. 4K is slightly less common but does also happen, with frequency depending on the streaming service.
The Grand Tour S04E03 4k web-dl is readily available on private torrent trackers hours after public release on Amazon Prime.
No idea what encryption Amazon use, but suffice to say it is thoroughly broken by someone out there. Given the expense of acquiring those presenters and the production costs of their shows, and how they bring people to the Prime video platform, I suspect Amazon is reasonably interested in keeping that content protected.
