I can see that problem, but that's surely an issue everywhere, even indie game development?

That it can be abused isn't a reason not to do it, just means people need to take more responsibility.

Plus, if were talking photos specifically, its easy to prove you own them via raw files (if they were taken on a proper camera).

Remember these "payments" are entirely voluntary, for small amounts, and its not like anyone is getting rich :)

But I do apprentice your point and yes, money can introduce its own problems. :)