Great question — answering as the UphillTech team:
There are no legally mandatory id checks on domestic and international flights within the Schengen area. Based on my experience: Many conventional airlines do not check passenger ids and many airports are fully automated, so that you when flying don't interact with a human being before being greated by a steward in the airplane. You check-in online, drop your bag at a self-service bag drop and even at the gate you just scan your boarding pass and go through a turnstile. Most no-frill airlines check the passenger id, but in their own interest, probably to prevent black-market sales of cheap and early bought tickets. So even if there is a name on the ticket, there is no problem getting a...
Full answer by Tor-Einar Jarnbjo: https://travel.stackexchange.com/a/185767 (CC BY-SA 4.0).
Need it done for your business? UphillTech.