“I work at a hotel and $politician came in with his mistress. Here’s a video I taped off of the security monitor.”

That's actually an excellent point, even if such technology worked perfectly it wouldn't solve simple problems like that.

Seeing footage literally taped by a phone off a NVR display is pretty common...

Yeah, but it also is usually pretty obvious about what it is. That's hard to cover up.

It's actually not too bad - you have to essentially line up the pixels on the camera's sensor with the pixels on the display, it's a challenge and might involve some careful choices of camera, display, focal length, distance, etc, but you only have to get it right once. This gets even easier with a projector where pixels can be blended together, that's why cam'd movies can be surprisingly watchable, despite being filmed in far less than optimal conditions, they don't show the sort of artifacts you're talking about. While poor contrast can certainly be an issue in such situations, think about how poor that setup is compared to what would be possible with a purpose built version.