French operator SNCF has previously asked passengers to self-declare as ‘Monsieur’ or ‘Madame’.
The EU’s top court ruled on Thursday that requiring rail passengers to declare a gender when buying a ticket is in breach of the EU’s General Data Protection Regulation (GDPR).
Probably whoever drafted the requirements for the software team just didn’t think to add a third option, and the software team didn’t want to add additional requirements.