What service is indirectly done by the rag-pickers for the disposal of waste?

The poor rag pickers make a living by sorting out reusable and recyclable items from discarded solids. They do a good job by removing much of the waste from the garbage dumps. Pieces of metal, glass, rubber, plastics etc., are removed to be recycled to get finished products. Thus, they segregate the waste and make waste disposal easier.