I once entered Germany at Bremerhaven on a private flight in a DC-3, from Ireland (where we had just been in the "in transit" lounge only - not cleared in by immigration). There were no German authorities around, so the air traffic controller stamped our passports - later in the afternoon, after we were settled in, and had had a nice lunch.
Last year, I flew from Amsterdam on KLM, to Bergen, Norway, and had my passport in hand upon arrival. Not only did the Norwegian authorities not ask to see it, they would not stamp it when I asked.
I don't know what the EU rules are, but they are apparently much more relaxed than those for crossing the Canada/US border! Last week, when flying commercial to California, US immigration would not let me enter the US, until I could produce a California street address where I would be staying. Lucky my client had emailed me my local hotel reservation, or I'd have been refused entry! Oh, and passports are mandatory for Canadians entering the US....