IOTL, there are two voltages used for mains electricity around the world; most countries use 240 VAC, while the US and a few others use 120 VAC. Likewise with frequencies: most countries use 50 Hz, while the US and a few others use 60 Hz.
But there's nothing, in principle, keeping countries from choosing 360 VAC or 480 VAC or even 600 VAC for their mains voltage instead, or using a completely metric electricity system (say, 1000 VAC 100 Hz). Or using a mains voltage lower than 120 VAC - maybe 60 or even 30 VAC?
So, what if there was a lot more variation in mains voltages and frequencies between countries than there is IOTL? What might we see?
(As an aside, it would be cool to see at least a handful of countries still using DC for their mains electricity - maybe small island nations where the lower transmission distance wouldn't be a problem?)