European thing - not just German.
It would be interesting to know if all the wiring is there for a rear fog light, or whether just a few connections are not hooked up.
Does it just make the drivers side light brighter (probably legal issues with that, as it may need to be a dedicated unit for fog lights), or do they replace that reversing light with a for light as they do on many European cars?
If all that were the case, you could purchase a drivers side light and have a rear fog light.