No idea how the system works, but if the clerk is able to disable the scanner and manually press a hidden button that plays the audio of the losing sound, seems like a pretty easy system to break.
Probably not many people do, but the point was made in regards to the comment that "a lot of people are cheated out of their winnings". I made the comment to simply point out that may have been the case in the future, but most modern lottery corporations have made efforts to eliminate that.