The game, like a notable number of other gambling titles, boots into an innocuous-looking game, but can be switched over to its actual gambling-related mode using a switch. The idea is that if an "arcade" owner in the relevant region ends up getting raided, the owner can simply cut power to the games and restart them, at which point they'll be in a perfectly legal-looking game.
The other typical scenario for such a game is that it will have a button combination to quickly put it into a non-gambling mode, in the event that someone is standing in front of the machine at the time that the parlor is raided. This isn't practically different from various MS-DOS games which had a "boss key", in order to fake the idea of looking like productivity software (or a plain command prompt) in order to not result in any reprisals.
As usual, you seem to be completely convinced that you're right about everything, and rather than approaching it from the standpoint of asking the reasonable question of "I don't seem to see anything gambling-related in Pucman, is this correct?" you brashly assert that the MAME developers are a bunch of fuckwits who have somehow YOLO'd their way into emulating thousands of machines despite apparently being so stupid in your view that they would eat their own shit if given half the chance. Maybe you should pause, take a step back, re-evaluate your life choices, and then fuck off to some other community that's willing to put up with your paranoiac bullshit.