As has been suggested, Getty Images (and other stock photo libraries) might have something to do with it.
People were searching for images on sites like Getty, Corbis, et al and finding the watermarked versions of pictures which were being offered for sale. Then (knowing that somebody else might have already paid for the right to use the watermark-free version on their website) using a Google Images reverse-search to track down a copy without paying the stock agency for it. Thus professional photographers (who sell their works through stock agencies) were being defrauded out of their rightful income and the stock agencies were losing their commisssion.
As an aside though, Diddlydo, you've been going the long way round to get the jpeg images you've been searching with. The need to use Paint disappeared when Microsoft introduced the Snipping Tool with Windows 7. (It's still there in Windows 8 & 10 of course). You can use it to grab any rectangular section of your screen and then save what you've got directly as a jpeg file.
The Snipping Tool can be found via Start > All Programs > Accessories but once you've got there it's best to RIGHT-click on it and select 'Pin to Taskbar'. Then you'll always have it available in a single click. (To use it, simply drag a rectangle around the area you want. Then go to File > Save As, ensuring that the file type is set to 'jpeg').