Less lights is less cost. On European streets the easiest way to detect an American-designed car is that they only have one reverse light, the bare minimum. Only suitable as an indicator to the driver behind you. Ever considered trying to reverse into a parking spot without any streetlight nearby? Reversing blind is awesome!

In any European car you get two lights, not in the center but in the corners so you can actually see stuff in your side mirrors while parking.

For a long time many German made car like from Audi, Seat, VW, BMW hat just one reverse light. On the left side is the fog light and on the right side is the reversing light.