Perhaps it can be enforced with a type of laser that doesn’t damage the human eye but completely obliterates a phone camera. As long as you keep the sticker on nothing happens to your phone.
"I've seen this on planet earth"
Afghanistan? China? Tonga?
But it's probably a nightmare from the liability perspective.
If we are asking for impossible things why make it so scifi coded? I would much prefer cute bunny unicorns who suddenly grow fangs and bite people who are taking pictures. They are both equaly realistic but the bunny unicorns are nicer to think of.