When was this? I lived in Reno for a while, and I remember having a similarly disgusted response to the trash strewn along the road when I happened to pass by shortly after the burn in 1998. My understanding is that the org has tried hard to deal with that problem since - there is certainly a lot of messaging before the event about where you can and cannot dump water or trash, and how not to be a dick to the locals, generally.

I didn't start going to Burning Man until after I moved to Seattle, so I haven't actually seen what the fernley-wadsworth road looks like post-event these days, but my impression of Hwy 447 going northwest is that it generally stays clean.