To be fair, there used to be quite a nifty version of Windows for embedded use. Not evident that this is being used here, of course… but it may not be a full desktop system.
Actually, using a mobile OS might not be a foolish idea: in the future I could imagine that these ads might interact with the individual passing them on the escalator, Minority-Report-style, and peering might be more reliable if you’ve got Android at both ends. Ha! 🙂