Still lower than minimum wage.
Again, not all of them. And it is still more money than you would make sitting in a college classroom.
It's particularly outrageous that some interns pay for the privilege.
Why? How is it any different from a college class? Shit, one could make an argument that an internship is
better than a college class because it gives you experience in the real world with people who actually do the job right now. For example, I'm a broadcasting student and the equipment we learn on (in our basic studio production class) is positively ancient, incredibly basic, and very behind the times. Even our professor wasn't an expert on the equipment, because he had never been on the technical side of the job until he got the professor gig. Real TV stations, on the other hand, tend to have more up-to-date equipment and people who are near experts at using it because they use it every single day. A friend of mine even got her "Advanced Studio Production" requirement waived due to the experience her minimum wage paying internship gave her. My school, at least my department, has a "not approved" list of companies who consistently used interns as either gofers (you're there to learn, not pick up coffee) or replacements for paid workers (you're their to learn as much as you can, not perform one task). There are companies that abuse the shit out of their interns, there are schools that don't keep a careful watch on their internship programs, but that does not mean the system itself is what has to be done away with.
Your earlier point:
Interns are basically slaves.
Is a MASSIVE overstatement, hyperbole worthy of the most whacked out nutjob. Slaves to not get college credit, slaves do not get paid, slaves do not resume build, slaves have no recourse if they are mistreated, slaves don't go home at the end of the night, slaves don't work for a couple of months and then go someplace else, and most of slaves have no recourse if they are mistreated.