It is called Poe's law, and Google returned it at #4. Bing or Duckduckgo don't have a clue...
2) They have a years of user's data, like for specific term, they see what users clicked most, so they see which results were perceived as most relevant. It is hard to catch up if you dont have such data.
3) They developed anti-spamming tools during the years of fighting against SEO-spammers.