Daytime running lights are still getting negative comments, and some may be valid. The initial daytime running lamps used the high-beam filament at reduced voltage. The high-beam headlight is designed to project some light rays upward to help in reading overhead signs.
Those upward rays of light, even at reduced intensity, can be annoying sources of glare, especially for drivers over 40. As we and our eyes age, the eyes become more sensitive to glare, and we also need more light to see than we did at 20.
It should be noted that General Motors is shifting away from high-beam daytime running lights to low beams or higher intensity position low (front park and turn signals) and to dedicated daytime running lamps on trucks. Perhaps the use of high-beam daytime running lights should be deleted from National Highway Traffic Safety Administration standards.
Daytime running lights are effective, as can be seen by results in Canada. The greatest benefit is during twilight hours, when many drivers forget to turn on the low beams.