Last year there was a spiritual/earth/hippy festival up the road from me called Finding the Light or something. There was a poster for it near my place banging on about saving the planet, taking responsibility for our actions and considering others. Good stuff, common sense, very commendable etc.
You should have seen the amount of litter all over the field after it finished! Even now there’s still some stuck in the hedges. And none of the organisers bothered collecting any of those oil-product-plastic-laminated posters held up with dolphin garroting cable ties..
If a bunch of sanctimonious tree huggers don’t care about littering then it probably doesn’t even cross the minds of most people.