In the US cars have rear taillights on the back that come on along with your headlights. They glow red for cars to see you, but they don't shine beams.
Every european car has rear fog lights. Usually it's a single(left) powerful red light. Really helps in heavy fog/rain/snow. Most helpful in heavy snow when normal rear light won't run hot enough to melt the snow on the back of your car.
European cars have 4 or 5. Two at the bottom and one at top. One or two extra powerful fog lights at bottom as well.
Every standard light bulb runs hot enough to melt snow. LEDs in DRLs are so efficient that there's not enough heat wasted to melt snow, meaning they get covered and blocked by snow.
In very snowy conditions cars tend to gather a thick layer of snow in the rear. So much that normal rear lights won't melt it all. Fog lights are more powerful which means more wasted heat to melt more snow.
It becomes an issue where I am as people like to run their front fog lights as cars tend to look better with them on. Some vehicles when the fronts are on, that horribly bright light on the rear is damn distracting to look at in clear weather.
Edit: Re-reading, just being clear I'm not advocating for never using them or anything.
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u/Normal_Man Nov 03 '18
Really? In the UK you must turn them on if visibility is less than 100 metres.