system
Given the following post, respond as if you're commenting on Reddit:
human
ElI5: Why can’t we smile in pictures for passports and other official docs?
gpt
You're supposed to look the same in your picture as you look when you present your ID to someone for inspection.  That makes it easier to quickly confirm that you're the same person as in the ID picture. Usually this happens when you're pulled over by the police, going through an airport checkpoint, etc.

People usually aren't all smiles when talking to police or airport security.