First mandated in Sweden. I think they are a good idea as most people forget that they are not to enable the driver to see but for others to clearly see his vehicle. A lot of people seem to be reluctant to turn on lights in poor weather conditions or dusk. Wide roads, narrow roads, it matters not a hoot. As their purpose is merely to indicate their presence there should be tighter control of how many lumens they output.
https://en.wikipedia.org/wiki/Daytime_running_lamp#Nordic_countries