Did you miss adjective "UnPaid" in his sentence with respect to the types of internships being discussed? There are paid internships too.
However, IANAL, but from what I recall there are no legal differentiations between "paid" and "unpaid" internships. Under the law they're both the same thing - which means there's nothing stopping employers from making all their internships unpaid.
Every little picofarad has a nanohenry all its own. -- Don Vonada