Your not from the UK I am guessing? We have strict rules around the use of fog lights here.
Yes I am in uk but from EU and ABSOLUTELY there are no strict rules here when it comes to illuminating the roads during the day or night.
Firstly the strict rules are actually IN EU. Here I was surprised (when I came here 12 years ago and still law not changedl ) many drivers during the day in old cars (before 2013 year cars) NEVER turn the the DRLs lights ON (as they don'thave automatic or newer car) which in EU you would be stopped and fined 50 euro. So DRL MUST be turned on all the time during day. Here we don't have to for sme reason...
Secondly the german car manufacturers (and then rest followed) after 2013 year started making cars that headligts DRLs will automatically turn on with ignition even if the switch is in position 0 that drivers will not get ticket every so often because it is very likely that many drivers forgetting to turn the DRLs ON.
Thirdly my Audi car is equipped with AUTO headlights (picture below) which MEANS not only for main beam but ALL exterior lights.
If I have it switched to AUTO it turns the main beam automatically according to the ambient light conditions. When is dusk or in tunnel. Fourthly, what you probably don't know is that the AUTO feature controls EVEN fog lights and depending what you have setup in MMi as well so mine a3 DOES turns my fog lights automatically depending of weather conditions and natural light conditions.. Coincidently, yesterday I was getting in car at night and there was very fine rain going on think it's called dews and I unlocked the car and lights came on INCLUDING fog lights.. I was really surprised when I got car.. First days I was like ; who turned the fogs on? So it does auto turn on, not only main beam... And am not sure but it may turn on even rear red "fog" lights it basically increases red light to use obviously in fog BUT mainly in downpour or spray when driving on highway, as you see better car in front when u need to turn windscreen wipers very fast.. When you see almost nothing...