Here's a neat story about how one student was implicitly recruited to one of them: http://www.theguardian.com/education/2014/dec/06/shimer-coll...
Jibran Ludwig – recounts to me the strange tale of how he ended up here. One night two years ago, when Jibran was 15, he was sitting in an Amtrak station in upstate New York reading Plato’s Republic and getting annoyed by the translation. The Greek gods had been given capital Gs, which struck Jibran as an erroneous Christian reinterpretation, and so he decided to abandon the book and try and find something closer to what Plato had intended. It was election night. The woman sitting opposite Jibran had an iPhone. So he went over to ask her the results.
As he approached her, his Plato in his hand, she looked alarmed. “Oh,” she said after a moment. “I thought you might be one of my students and I didn’t recognize you and I felt embarrassed.” She explained that she was Susan Henking, president of Shimer, “and Plato is the kind of thing we read”.
“If the president of this college thinks I might already be there,” Jibran suddenly thought, “maybe it’s where I should be.”
Yeah that's not a fact at all; it's just your opinion. This is why I agreed with the other poster that this wasn't a great thread of argument; we're just dick-measuring based on our own experiences at this point. You can attempt to try to bring in what you believe to be "objective" measures (like course requirements), but 1) those measures are themselves questionable, and 2) the selection of criteria to judge is itself a subjective judgment.