To my understanding some of those early arcade games also had jumpers to control some of the behavior. It could be that a tech set the "free credit on reboot" jumper and forgot to reset it when they were done.
I think they still use these in bars
Those systems are occasionally used in bars in the US, though they've dropped the whole plate and it's usually just arms where the holes are.
To my understanding, at least in the US, they aren't used for deep-cleaning anything. That happens with soap and water in the back still. The upside-down-showers are used to clean out the dregs of someone's glass when they get a refill (you give them a glass, they give it a quick rinse, refill it and hand it back), and as a quick rinse for new glasses to clean up water stains/detergent residue and anything that might have fallen in since they were cleaned (hair, dust, etc).
Actually here is a link explaining it: https://www.webstaurantstore.com/article/620/three-compartme...
Mileage obviously varies, but the "beer nerd/snob" bars I've been to simply don't re-use glasses without a full wash. They'd rather just charge a little more to hire more dishwashers and be able to absolutely guarantee that there's no leftover beer/water in your glass when they refill it, and that the glass is refrigerated if that's something they want.
I've always heard the head/foam had more to do with how you pour the beer (more impact/movement = more foam), but it makes sense that temperature affects it as well. There's some kind of official course on how to pour Guinness to get the correct head on it. I don't remember the whole thing, but it was something about holding the glass the correct distance from the tap and tilting it so that the beer "slides" down the side of the glass rather than a direct perpendicular impact with the beer already in the glass (which makes more foam).
Yes, the glass's sides are still full of the disgusting soapwater from the bucket that's now basically 95% other people's drink dregs.
From a health perspective, I'd be more worried about the leftover sanitizer in the water in the glass. Bleach is pretty common, and it's honestly a tossup whether I'd rather drink someone else's dregs or bleach. It's probably the dregs, I'll take a stomach flu over melting my stomach lining with chronic low-grade bleach exposure.