There's a big fence around Glastonbury - and wandering off into the Somerset countryside doesn't hold the same level of risk as walking out into the desert...
I know Burningman has a _very_ strong "hipster douchbag" reputation these days (and I won't argue that it's not at least somewhat deserved) - there is definitely something more than that as well.
(1) http://galleries.burningman.com/photos/klammerd/klammerd.995...
(2) http://galleries.burningman.com/photos/silver/silver.3577
(3) http://galleries.burningman.com/photos/mr_fang/mr_fang.21326