This would definately trigger my pedant button, factory accessory is an oxymoron. However, like many technical terms, across many industries, things get mis-labelled and mis-quoted until they become common parlance.
Anything that is added after the car is a "local fit" or "dealer fit" accessory, often with the word "Genuine" added in for good measure. Which if those lights were added in Palmy would be the case for these lights. These terms have particular relevance when cars are modified or tuned at the dealership - ie a BMW M Performance power & sound pack is added to a car, as this affects things like the emissisons and fuel consumption, etc. but this does not have to be recorded in the MVR / fuel saver information. If the same part were fitted at the factory it would affect the official information stored on the MVR. A technicality maybe, but a legal one.
End of pendantry.
Just out of mild curiosity are the lights actually BMW parts, or from an aftermarket supplier?