> heck, only Japan is 110V besides the US as far as I know

Japan is an oddball by being 100V.

US is 120 and that extends pretty far south (and north).

https://en.wikipedia.org/wiki/Mains_electricity_by_country

I’m semi amazed motor vehicles are as standard as they are with 12V and the same socket worldwide. I guess the tobacco industry is a great unifier.