Why do some cars have only one reversing light?
The reason why many cars have only one reversing light
is cheapness of conversion from LHD to RHD. It is mandatory to have a
single rear foglight either in the middle of the vehicle or on the offside -
thus a single foglight has to be moved from LHD to RHD.
In Europe and other countries adhering to UN Regulation 48, vehicles must be equipped with one or two bright red "rear FOG lamps", which serve as high-intensity rear position lamps to be turned on by the driver in conditions of poor visibility to make the vehicle more visible from the rear. The allowable range of intensity for a rear fog lamp is 150 to 300 candela, which is within the range of a U.S. stop lamp (brake light). Rear fog lamps are not required equipment in the U.S., however, they are permitted, and are found almost exclusively on European-brand vehicles in North America—Audi, Jaguar, Mercedes, MINI, Land Rover, Porsche, Saab and Volvo provide functional rear fog lights on their North American models. Most jurisdictions permit rear fog lamps to be installed either singly or in pairs. If a single rear fog is fitted, most jurisdictions require it to be located at or to the driver's side of the vehicle's centreline—whichever side is the prevailing driver's side in the country in which the vehicle is registered.This is to maximize the sight line of following drivers to the rear fog lamp.
So jurisdictions permit single fog lamp, so for cost cutting companies only provide single fog lamp and reverse lamp instead of pairs of lamp.
Source: Wikipedia
