I guess the gurus should be able to answer my question.

In SA we have 380 volt 3 phase supply to e.g. a factory. From phase to neutral we have 220/230 volt.
Why then in USA is the supply 220 volt three phase and 110 volt from phase to neutral ?
I am specifically referring to the difference from 380 to 220 ( 58 % ) and in the case of USA ( 50 % )