Google has safe harbor under the DCMA. Google's business model is content use -- Google uses your content in fair use unless you tell it not to. They are riding a legal loophole. All search engines have this DCMA exemption.
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There is a button to [visit page] in Google Image Search but I don't think it is used much ... Google Image referrals don't monetize. However, if the referral is to an image -- your server could watermark the image -- at least you would get the branding value -- if the image is reused or posted you will get your name out without doing anything shady
