It' often (too often) also headlight adjustment, IE. poor headlight adjustment. Headlights are in adjustable mountings, and those mountings often shift slowly over time or have just never been properly adjusted.

Then there's those who put in brighter or directional headlight bulbs and don't re-adjust the mounts to accomodate the the more powerful and different beams. Then also those many who simply drive on out of town roads with their brights/high beams on basically all the time.

High beam lights aren't supposed to illuminate the trees, people... -_-