Fair enough - DRM is a thing. Its not typically the most robust thing, but people have certainly tried and modern cpus have secure enclaves that make implementing such a thing sort of fesible (see for example widevine).

However ultimately at some point, you have to convert the image to photons to look at it, and its pretty hard to prevent someone from taking a photo of those photons. I guess you could require every camera to auto recognize copyrighted work and refuse (think EURion constellation or Cinavia) but that is pretty orwellian and you still have plain old analog cameras.