That only works at such a low price to the contributor if there are enough other buyers wanting these files.
In a different example there's a UK magazine called Gardening Answers which uses a lot of SS images (and from Alamy and specialist sources), for plants hopefully correctly named down to the exact cultivar. But of course, once they have them, they're on file for the next time they need that plant, as as they're mostly using SS files at postage stamp size, they're cutting bits out of an image, and the next time, they could cut a different crop, so that smart readers won't notice.
But unless there are a lot of similar users, it's hardly worth going into even your own garden and setting up the shots (these are mostly 'in garden' shots, not studio setups, or at least they look 'in garden'), 'gardening' away distractions, selecting perfect specimens etc. for 25c - 38c (I can't imagine these uses will generate higher value sales), far less travelling around looking for more and more different species/cultivars. If there are multiple publications throughout the world needing that content and buying from SS, it could possibly work for the contributor.
Cheap files work for the buyers, obviously, but only 'mass interest' cheap files work for the contributor.