I've often looked through such lists as these and pondered over the reasons why certain places ended up with certain systems -- Colonial influence, proximity to other industrial nations, etc.
Some of the lists seem to be a little inaccurate (to put it mildly), but the Kropla ones don't seem to have any glaring mistakes.
The definition of nominal voltages is open to argument and political wrangling, however. As the list shows, for example, officially the U.K. is now a 230V country, although in practice in most areas nothing has changed since standardization at 240V some 30 years ago.
The "electrical bureaucrats" here decided to fall in-line with the EU-mandated 230V standard by simply adjusting our allowable supply tolerances. Previously it was 240V +/-6%, now it's specified as 230V +10%, -6%.
