Warning the user that it may be illegal to take photos is reasonable, but making a device that acts on the theoretical authority of someone else against its own

Warning the user that it may be illegal to take photos is reasonable, but making a device that acts on the theoretical authority of someone else against its own/possessor is not. Taking your example of polls, it may be illegal for me to take a photo, but it may be my responsibility to do it anyways. For example, I may see visual evidence of large scale voting fraud within a polling station. It is similar for sensitive data and whistle-blowers.