Definitely not all of them, Austria even rolled back because it removed the visibility advantage of motorcycles and because daytime running lights are an arms race that some legal road users cannot keep up with. It makes those with no light (or with significantly weaker lights) practically invisible because drivers will inevitably reduce attention to the common case.

If your car cannot be operated legally, it should not be operated. You don't need automatic DRLs, you can always just turn your lights on.

I think usrusr is referring to non-car road users. Bicycles and motorbikes need to stand out from cars, but can't keep up with them in a lighting arms race due to power and weight.

And ox-carts. And walkers. And all kinds of other long tail surprises. The distinction between limited access roads and the regular kind exists for a reason.

I think it's mandatory that new cars have always-on lights, rather than being mandatory to turn on your lights all the time (if you've got an older vehicle). That's how it is in the UK, anyway.

Mandatory for cars type-approved after the 7th of February 2011 [1], not all new cars. Some manufacturers were selling models that were type-approved before that date for years later (the Peugeot 3008 is one example), and therefore weren’t required to have DRLs.

1: http://europa.eu/rapid/press-release_IP-08-1394_en.htm

Motorcycles maybe, cars have (by now) mandatory daytime running lights, but at least in Germany for older cars it's not mandatory to have lights on during daytime.

Worse, some of the daytime running "lights" are only visible from about 5 m directly in front of the car - plus on most cars, the "daytime lights" setting only switches front lights, leaving the back entirely off. That's a cure worse than the disease.

I remember that one country reverted its decision for mandatory daytime light for cars because it decreased visibility of motorbikes (for which daytime lights were mandatory).

That would be France. The idea is indeed to increase visibility of the most vulnerable vehicles. Motorbike riders behave differently than car drivers, hence it is critically important to be able to distinguish them easily in traffic (we downright suck at evaluating movements of light sources compared to solid objects). This is also a factor as to why always-on daylights are mandatorily placed lower than headlights.

In Croatia it's only during winter time for cars.

The EU has required DRL's on all new cars since 2011. As an EU member state this applies to Croatia too.

That may be so, but on older cars you don't have to turn on your low beams when it is daylight savings time.