These trash piles are not because the residents don't care, or that they don't have anything to do with the trash. No. It is because they use trash as fill -- to fill in the swam so that it becomes "land" and they are able to build on it. As the community keeps adding trash to the above area, it will become more and more solid and in a few years, homes or other buildings will be able to be built on this space.
The roads in San Mateo used to be all like you see in the picture above. They call these 2x6 structures "London Bridges" and that is how everyone got everywhere. But the community organized and worked together to make a solid main road in the town and also some solid side roads.