Your original comment was unclear on what the differing credentials would be used for, and it's not a bad idea. It does depend on people being conscientious in

Your original comment was unclear on what the differing credentials would be used for, and it's not a bad idea. It does depend on people being conscientious in public and using the passcodes appropriately, but programming can't mitigate that much. I'm more concerned about how much a phone is expected in the first place, for more and more things. Last year I went on a trip with some friends, and half of the places we went required apps for tickets or even parking, and even a hotel we stayed at was strongly pushing an app. If I'm flying somewhere, I still get a printed boarding pass because I don't want my phone to be the single point of failure that prevents me from flying if a freak accident happens between check-in and the gate.