Stock photography doesn't pay well at all, so I can understand why some want to give it away for free.

I have a 7k USD gear, shot thousands of pictures, and put the 50 best ones on Shutterstock, I had 5 sales, and 3 were for one picture. I made a total of $0.89 USD and am still well bellow the withdrawal threshold.

It was not even worth the time uploading and annotating the 3 pictures that eventually sold.