So if google want to train general image classification to pick out things, e.g. road signs: google can use their 4D datasets to select a gazillion real still

So if google want to train general image classification to pick out things, e.g. road signs: google can use their 4D datasets to select a gazillion real still images that contain what they _know_ are road-signs or not road-signs or whatever. And then they can feed these to their image classification stuff. How does humans clicking on tiles help train their image classification AI?