Question

why In USA domestic voltage supply is 110V but in India it is 230V?

Answer 1

because USA needs less power supply
HOPE THIS HELPS

Answer 2

Almost the whole of the world uses a frequency of 50Hz and a voltage of 220-240(higher voltages for better efficiency in transmission). The exception, where 60Hz is used (with a voltage of 110-120), is the Americas (North and South) and the Caribbean (and parts of Japan and Korea).
Early in the history or electricity, Thomas Edison's General Electric
company was distributing DC electricity at 110 volts in the United States.
Then Nikola Tesla devised a system of three-phase AC electricity at 240 volts. Three-phase meant that three alternating currents slightly out of phase were combined in order to even out the great variations in voltage occurring in AC electricity. He had calculated that 60 cycles per second or 60Hz was the most effective frequency.
Tesla later compromised to reduce the voltage to 120 volts for safety reasons.
With the backing of the Westinghouse Company, Tesla's AC system
became the standard in the United States.
Westinghouse chose 60 Hz because the arc light carbons(arc lamp) that were popular at that time worked better at 60 Hz than at 50 Hz.