Originally Posted by corporate-wage-slave

The ticket name and API data are for two different people. Immigration authorities want to know who is planning to arrive, they look at API and test to see if they are OK with the data. Airlines are only interested in ticket names and are interested in two features - will the person get into the arrival country without leading to a hefty fine to the airline, AND has the ticket been issued to the right traveller (so no reselling of tickets on to someone else). Of those three tests, your traveller appears to have had no problem with the first two, and within the EEA there is freedom of movement anyway. So the gate agent checked it was an EEA passport and was at that point it was clear that entry would not be denied. For the third test, it's up to the airline to challenge if they wish, and clearly your companion did have the paperwork to meet this challenge. Some airlines are more ruthless at revenue protection than others, so I'm not sure what would be the point in buying tickets in a married name, travelling under maiden name (I can understand the reverse to a degree) since it seems to be potentially unnecessary hassle. But this is all about a commercial policy rather than the law.