It's a funny story in the US, at least from my perspective.
We are officially supposed to be 120VAC, 60hz, but depending on who you ask, some people will say the US is 115V, 110V. There are all tolerances, and these numbers are still within them, but all my meters (on a UPS for example) stay right around 120VAC.
It gets even crazier in Japan. They have 100VAC power at either 50 or 60hz depending on what half of the country you are on. They also use essentially the same NEMA standard the US does, just with a different name, and from what I can tell they have some plugs that look like they come from the 50s (small housing, thin wire), no meat to any of it). Grounding also seems to be a bit up in the air with some places having it, some places not, some places having ungrounded sockets with a grounding post on some socket? I don't live in Japan, so I can't confirm any of this to be a thing on a large scale, but I know it exists.
We have so many standards for all of this, but nobody can standardize the standards. We even have over 20 different organizations across the world that do standards, like DIN, ISO, IEEE, IEC/CEE, NEMA, BS/BSI, JIS, the list could go on and on.
Anyways, sorry for being a random Yankee passing through, carry on.