The EU and Japan, for instance, do have exit checks. Not if you leave from an airport in the Schengen area to another Schengen airport. Some airports may chec

The EU and Japan, for instance, do have exit checks. Not if you leave from an airport in the Schengen area to another Schengen airport. Some airports may check your ID (and determine if it matches your boarding pass) before allowing you into the restricted, passenger only area. But others don't. In Vienna and Zurich you just automatically scan the bar code on the boarding pass and an automatic gate admits you. Some of the gates now even have automated gates where you scan your boarding pass and get admitted to the plane. There is also no entrance check, when you arrive from a Schengen airport. I usually don't need an id when flying within Schengen (Prague being one of the exceptions), just the boarding pass, which I usually print at home. Please note that I don't recommend not to carry id. Even if you're usually not asked. If they do check at the gate you're quite obviously not boarding when you don't have a valid id.