Let me ask you this. Isn’t it possible for objects behind the Black Hole to show up as a ring around the hole do to the bending of their light as it passes the parimeter?
I suspect the pull of the Black Hole focuses at some aspect of the hole. This may prevent what I’m referencing. If the gravity has it’s most pull around the mouth, it might be possible.
At any rate, I’m probably referencing artistic license from depictions I’ve seen over the years. It would be hard for Hollywood to show a black hole on film if there wasn’t some light to differentiate the blackness from other blackness.
you sort of answered your own question. That's Hollywood!
Black holes are totally devoid of light. The only way I know they can be detected is by the erratic movement of mass around one, or once suspected a massive escape of Gamma Rays. I'm certainly not an expert but was always interested in cosmology.
I suspect that artists in both film and print used a lighter ring on the exterior to give us a reference point.