The EU has done lots of reach on road and car safety, there's lots of data out there - just perhaps not in the US as many American made cars have significantly lagged behind in terms of safety features.
I don't know if it's an EU rule, but in my (European) country cars are required to have their lights on at all times, even during the day. The lights switch on automatically when you start the car
I'm baffled that daytime running lights are not mandatory on all models of all cars in 2025. My 13 year old Grand Caravan has them, though I suspect it's because it comes from the Daimler Chrysler era.
After I visited Iceland where it's mandatory, I liked the improved visibility so much I turn my lights on for every single trip. It was not a takeaway I was expecting to have from the trip.
It's a good idea in some places. An overcast winter's day in the North isn't that well lit by default.