In defense of pilgrims in general, it only takes an occasional litterbug. I followed a group of teenage school pilgrims one morning. They stopped at a vending machine, bought candy and chips, and for the next hour, I watched them leave a trail of of discarded wrappers! There was not any peer pressure, or an adult leader, to urge them to carry the trash to the next disposal area. No one in the group of about twelve would admit to speaking English, but I exchanged greetings with them for two days, and they were very nice kids. They just were not thinking about keeping the environment clean. One person with a can of paint or a Magic Marker can leave extensive graffiti, and one person with no regard for the cleanliness or appearance of the Camino can leave a mess that lasts days or years (orange peels never degrade, by the way; tissue may last only until the next big rain).
Someone is bound to ask, so, yes, I did pick up after the kids since their mothers were nowhere in sight.