Zillow's "Coming Soon" listing--what gives?

There was an interesting "Coming Soon" listing that I saw on Zillow that said a property would be on the market on a certain date. It never did appear, and then a few weeks later, I see it sold for a much lower price. Are these type of things not really "Coming Soon" but actually for sale? I'm assuming someone just called and gave a cash offer? But why would someone not wait to see what offers came when it was truly on the market?