While the ticket machines of the Austrian railway service (ÖBB) run Windows CE (on what looks like a regular PC), I think the info displays use some kind of Unix. Well, >10 years ago (where the info displays weren't widely deployed) in the middle of the night one showed the standard X11 background, a X shaped cursor and a terminal with scrolling text.

You only know the OS if something goes wrong. Maybe all the displays that are ok use Linux/Unix/something else?