Except there is a huge legally and socially understood difference between "your apartment" and "Burger King". It would be totally different if dude had overhea

Except there is a huge legally and socially understood difference between "your apartment" and "Burger King". It would be totally different if dude had overheard this coming from open window of home and taken pictures through window. I would expect (no idea if so) that to be a criminal and/or civil invasion of privacy. Privacy is not inherent/automatic. You have to take steps to establish privacy (move to private space being most common) before your privacy can be violated.