*generalization*
The "fog" lights on the 4R (and most cars for that matter) are not true fog lights - they are driving lights. Hence, they are designed to only come on when you have your headlights on. "True" fog lights will be independent of headlights and have a separate switch.
Also, as noted above, fog lights usually have lenses that cause the light to spread in a wide horizontal pattern (as these LED light do), or they can be that yellow high output light you sometimes see (they don't have to be yellow). But yes, they should be lower than the main lamps and have a focused beam that would keep the light low and wide for slow navigation in fog/heavy rain/snow.
I'm very much confused.
I don't know if European regulations are different, buy my Mercedes
has fog lights that can operated independently in the following modes:
(1) front fog lights ON, low-beam OFF, high-beam OFF
(2) front fog lights ON, low-beam ON, high-beam OFF
(3) front fog lights ON, low-beam ON, high-beam ON
Turning on the high-beam does not affect the fog lights, because the fog lights is only turned on/off via selecting it on the light switch. When your
turn off all the lights and lock the car at night, the fog lights come on and
illuminated the front for 30 seconds, then turn off automatically.
On my Toyota and Lexus vehicles, the fog lights can only turn on with low-beam. When high-beam is activated, the fog lights turn off. This is totally different than Mercedes.
On my Chevy truck, the factory fog lights can be operated independently from the low-beam, but they automatically switch off when the high beam is activated.(but not when using flash-to-pass high-beam)
If I had to guess, there is really no strict USDOT regulations.... each manufacturer does its own thing(as long as it's logical and safe)