I think because most of them are going out of bounds at the resort or the avy is inbounds at the resort, so people are looking to fault the resort not the actual victim...
I am a skier and a sledder, I ski mostly the backcountry and use my sled to get there, I also like to tear it up in the swamps and the occasional hillclimb too, I've seen both skiers and sledders head into the backcountry without gear and knowledge, even been on a few rescues...I've also ridden and skied with some very educated backcountry travellers, who have knowledge, experience and the right gear...
Bad press comes from the stereotypes that people use, just as you did calling the skiers "greenies", I'm sure they use the term "motorhead" just as freely...
It doesn't matter how well you educate or tell people not to go, there will alwyas be people who ignore the obvious and head out anyway, but I think pure backcountry skiers get just as much bad press as the sledders, its possible you just aren't finding it...