It is "trolling" in the sense of the original metaphor of troll fishing - make small demands from a huge number of small cases and get a decent total payment.

It may also be trolling in that it's not the photographer making the claim, but some company that buys rights specifically to do this kind of bulk demand.

Finally there is a sense that it is a very minor infringement - one where there would never have been a chance of a photographer making money off it in the first place. I don't think this is really a good justification, but might make the site a bit more miffed about the demands.

For the cases of copyright trolling and patent trolling, the metaphor comes from the “Three Billy Goats Gruff” story: a troll just sits there under “his” bridge until someone walks over the bridge, then he jumps out and threatens them. That’s more akin to what goes on with copyright trolling.

You're thinking of "trawling", not trolling.

"Trawling" and "Trolling" are both fishing terms, and trolling fits here just fine.

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https://dictionary.cambridge.org/us/dictionary/english/troll... trolling noun [U] (FISHING)

the act of trying to catch fish by pulling a baited line through the water behind a boat:

well if this encourages people to check photo licenses, I see that as an absolute win for photographers.

there's plenty of high quality photo on unsplash anyway, and people really ought to know the difference instead of playing ignorant.