As a hobby, I restore pinball machines. A modern one is extremely careful about how it uses power, limiting wall current to a small, normally-sealed section of the machine. And even so, it automatically disables the lower-voltage internals the moment you open the coin door. A 1960s machine, by contrast, may not have a ground at all. It may have an unpolarized plug, and it will run wall current all over the place, including the coin door, one of the flippers, and a mess of relays.
In the pinball community, you'll find two basic attitudes toward this. One is people treating electrical safety about as seriously as the people who design the modern machines. The others is people who think anybody who worries about a little wall current are all pussies who don't have the balls to work on anything and should just man up and not worry about a little 120V jolt.
The truth is that most people here are not engineers of any sort. We're software developers. We're used to working in situations where safety and rigor basically don't matter, where you have to just cowboy ahead and try shit. And that's fine, because control-z is right there. I've met people who bring that attitude to household electrical work, and they're fucking dangerous. I know one guy, quite a smart one, who did a lot of his own electrical work based on manliness and arrogance, and once the inspector caught up with him, he immediately pulled the guy's meter and wouldn't let him connect up to the grid again until a real electrician had straightened it all out.
It's true that this stuff is not that hard to learn if you study it. But an architect friend likes to say that the building code is written in blood, meaning that much of it is there because confident dumbasses managed to kill enough people that they had to add a new rule. If people are prepared to learn the rules and appreciate why they're there, I'm all for it. But if they do it coming from a place of proving that they're not "so afraid of residential power", that's a terrible way to approach it.
