At the passport control kiosks, they can just scan your face and give you an exit ticket. It was super quick, and surprising. I was able to skip talking to an immigration agent completely. They can do this because they have photos of me from previous kiosk visits, and because they can restrict the universe of photos they need to check to just those who were on recent flights. I wonder how well it works for twins traveling together or something. For any level of uncertainty, they can just have you go talk to a human instead.