Is there a reason headlights and windshields dont use the properties of circular polarized light? reflections reverse the circular polarization state.

standardize the polarization filter on windshields and headlights, and unreflected direct light (from other cars) can be filtered out, while softer diffuse single reflections (from both your own headlights and those of others lighting targets like road etc) pass through the windshield...

For cyclists and pedestrians one could make "night glasses" that do the same as the windshields... and similar bicycle headlights with circularly polarized light