... But in countries like USA they give 120 step down from 240 for whatever reason and not different phases unless its a commercial/industrial setup...
Not quite. You have 220/240 in your home for the electric stove, clothes dryer, A/C unit & ....
While there is a step down transformer on the pole (or in a box) for distribution lines at 13,800 volts (typ.) down to 240 secondary side, there is a center tap to get 120 from each leg to the center tap for the 120v "neutral".