DRM Hell

Amazon Prime, like many services, is a DRM hell. It won't go to over 480p on Firefox on Linux at my end. However, instead of a rant, I am interested in why this is happening. Say, I rented the same film from YouTube Movies(Yes, such a service exists) and the quality can toggle all the upto 1080p but the same title on Prime Video is stuck at 480p. Is it because both services use two DIFFERENT kinds of DRM?