I'm going to step back in and agree with just about everything said. I've been on many trails thru National parks and seen the litter strewn along pathways. I saw a male and female ranger go 100' down a side of the Smokies and disappear while hiking to Abrams Falls, so steep they were holding onto brush to both descend and then come back up. All to retrieve several soda cans, water bottles and some dorito bags.
What are folks thinking when they look over the canyons, at the same time dropping a Gatorade bottle? That the rangers will pick it up?
What are they thinking taking trails listed at moderate or difficult, in only flip flops, with no water, and a cell phone in their face? That everything is like tv?
If people could police themselves, show some responsibility and some respect, things probably wouldn't get to this. However, I suppose charging for the trail may encourage some of the casual, out of shape, ill equipped, insensitive sorts to photo the trail head and watch the rest of the hike on youtube.
It's too bad it has to be that way.