Lots of arcade games and other amusement machines made in the last twenty years run on desktop Linux.
Incredible Technologies games, Raw Thrills/Play Mechanix Big Buck Hunter Pro, Arachnid dartboards, and TouchTunes jukeboxes off the top of my head.
Employees can daily clean as much of the machine as they can access, and there will still be a bit of black biofilm in there (not mold). The same biofilm lives down in all of your sink drains.