I believe PAT is important. I do not use chargers from eBay and buy transformers from places like RS Electrical and CPC with a datasheet and proper markings that actually mean something. I don't want a cheap import with fake markings to damage me or my computers.
I'm not an electrician but testing an original arcade machine would have to be very thorough. Every exposed metal part, monitor, button, speaker and socket need tested. A MAME cabinet would be easier I guess with PCs and flat screens.
An electrician told me there is a difference between electrical installations and electronics. Another very good electrician also diagnosed a duff Jamma transformer in my OutRun. They have all the experience and test equipment.
In general electrical testing is essential and should be recognised more by the public.
Big Clive is excellent. His teardown of this dangerous multiplug is great:
David Savery (DSES UK) also had a savage review of one of those. He had to diagnose a fault when an RCD tripped. It almost caused a customer to be electrocuted when an iPad was plugged into it, charging and she touched a radiator. He crushed the multiplug under his van. I can't find that one though.
I also like John Ward who tested those:
That should be on Watchdog.