> When I was younger you could stare at the yellowish glow of a car with headlights on and just not be blinded.

The older incandescent bulbs were a different color temperature (more on the yellow side of the color spectrum) and were not a point source (filament instead). Both contributed to them not seeming quite so bright, even if the net lumens was the same.

The newer LED's are much more on the blue end of the color spectrum (automatically making the same lumen level appear much brighter) and the LED's are much closer to point sources, which further makes the result appear significantly brighter even if the lumen level was the same.

Couple the "harsh blue light" and "point source" with "significantly more lumens" as well and you get modern headlights that are painful to look towards, much less to look directly at.