In some european countries (especially the ones up north) it is obligated to drive with the lights on during 24h per day. This is a good thing; it makes the roads a lot safer to drive.
In europe we have a lot of narrow roads with a lot of trees besides the road. If the sun is not shining and the rain starts to fall down, the visibility gets very bad...there are a lot of drivers on the road who should not be there (we have a lot of "blind" drivers...).
Especially when one has a dark car and tends to drive to fast (like me), it is very wise to carry the "daytime" lights during the day.
I think that it depends on the situation itself and the traffic on the road whether you see someone coming or not.
In the states the roads are wide and people do not drive that fast; here the roads are small and some european loonatics (...) think they are in a excessive hurry and drive speeds up to double of the allowed max speed...
daytime running lights is a good thing...I always drive with my lights illuminated 24/7...
with a minor 600+k