I just flew from Zurich to Paris and back. The only ID check was by the airline at the gate in CDG. On the other hand, when I flew from Athens to Zurich they (

I just flew from Zurich to Paris and back. The only ID check was by the airline at the gate in CDG. On the other hand, when I flew from Athens to Zurich they (spot-) checked everbody's IDs and passports at the arrival gate. I fly a lot and very rarely need ID. This doesn't mean that you shouldn't carry it and depending on the airport it may be checked.