I just got back from Internet Librarian 2017 (in beautiful Monterey, CA — tough assignment). Among the insights I’ve brought back are:
Google Image search is focused more on matching meaning than matching images. If you want to search for instances of an image (to watch for usage of your organization’s images or to find mentions of a chart or graph in a report or article, say), you’re better off using a reverse-image search tool like TinEye instead.