I think there are a ton of different situations, and certainly sometimes unpaid internships can be exploitative, but I wouldn't agree that by definition they are. Either way, our article is more about the legal issues than the ethical ones. I suppose I should've said "some times when it's legal not to pay them." :)
>>The employer derives no immediate advantage from the intern;
If the intern is doing work for free that the employer would have to have a paid employee perform, they are gaining an advantage and therefore are violating the law.
Can you honestly give an example of an unpaid internship where the employer is not gaining an advantage? If so, then it is fine to not pay them. But those are very, very rare. My opinion, obviously, but I can't think of a non-contrived example.
I don't know if unpaid internships are technically considered "hiring", but I think that is the root of the misunderstanding. All the implications of the word "hiring" that I can think of violate your 6 point test. You don't hire people to educate them, or to benefit them primarily, or to not do something your employees would do.
