| To the best of my knowledge, there was no worldwide conference on | selecting a global electrical standard as there had been for setting | the world's time zones (The French insisted that the prime meridian 0 | degrees longitude must run through Paris, but the British held out for | Greenwich, and won!) . Perhaps, at the time, the big industrial | concerns like Siemens were interested in protecting their markets, but | I think the choice was made without even imagining a global market for | electrical products. In Europe, even though the voltage and | frequency were standardized throughout the continent, every single | country had their own unique plug and socket arrangement that persists | to this day.
And what was the frequency dependency of the primary consumer electrical product of the day? None. It was the light bulb. Industry had some concern since much of their usage was motors. But motor systems could be engineered around it easily enough.
| I still have trouble understanding why Japan is at 100 volts and half | the country is at 50 Hz, the other half at 60 Hz. Does anyone know | the particulars?
I'm not sure about the 100 volts, but the frequency difference could have been just from two major hold outs. At the time they didn't need to form a shared grid, so the remaining issue would be dependency on stuff that used the power. And it's not the critical.