I think it's some combination of laziness or not knowing how their vehicle works. Some are coming equipped with auto high beams, but I'd wager those don't work on windy roads and therefore don't automatically dim.

On the other hand, I was driving at dusk last night to church and someone had his high beams on (still fairly light outside as the sun had only just set) and it was an older vehicle. So, I'm sure there's some laziness/ignorance to the high beam problem.

You're definitely not the only one noticing this!

(Don't get me started on squatted trucks...)