If Getty licenses images for others to use, how is Google supposed to know they own a particular image? Getty needs to put something in the image metadata to show it is copyrighted, and then ask Google to refuse to show images with that metadata (or have a court force them if they won't do it voluntarily) They can use a reverse image search to look for copies of their images without the metadata, and go after the web site owner for violating their copyright (or maybe ask that google block those copies automatically if they've indexed that same image with copyright metadata)
It sounds like they want Google to quit indexing full sized images and only do thumbnails, making it harder for people to find images on their own - leading them to go to Getty's site and purchase stuff. While it may not be a good situation that people think they can do an image search for "church in a meadow" or whatever and download whatever they find without worrying about copyright, Getty's images are a small part of the web. That would be like JK Rowling suing Google because a few people have copied the text of her Harry Potter books onto the internet and it is findable with a search on "harry potter", and she wants that search term blocked.