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I see your bright LED headlight post, and I respond with matching LEDs, one sanded down a bit to diffuse the light.
(lemmy.world)
The top one is diffused, bottom one untouched and only shining forward like a laser.
This is obviously no special flashlight, but rather a simple example of how to fix/address the obvious problems with blinding LED headlights mentioned in this post..
It'd be possible to mount detectors by the side of the road that automatically trip on mis-mounted headlights.