Foglights point directly at the road in front of the car so do not reflect glare back from the fog itself. But the ancient RVLR rules the Highway Code refers to are overridden by Commission Directive 2008/89/EC of 24 September 2008, amending Council Directive 76/756/EEC, that make DRLs a compulsory fit on new cars from 2011. Already, new Mercedes, Porsches and Renaults and many others have LED DRLs where 'foglights' used to be. Just look at the cars passing you in the street. I have not seen any announcement that this has been incorporated into UK RVLRs, but it must have been otherwise the UK would be in breach of an EC Directive.