street sweeper vs waste picker

street sweeper

noun
  • A person who is employed to sweep streets, pavements, and gutters, keeping them clear of litter. 

  • A machine used to sweep streets. 

waste picker

noun
  • A person who salvages reusable or recyclable materials thrown away by others to sell or for personal consumption. 

How often have the words street sweeper and waste picker occurred in a corpus of books? (source: Google Ngram Viewer )