By the way, "half" is a slight over-statement.
If you have a 20 amp circuit hooked to a motor with a 20 amp draw and the length of 12 gauge wire from the motor to the panel is 50 feet, you get . .
120 volts has a 2.7% voltage drop
240 volts has a 1.5% voltage drop.
Increase the wire size to 10 gauge and the 120 volt circuit only has a 1.6% loss. Use 8 gauge wire and the drop with 120 volts is only 1.1%.