Why is it that most companies request that a person be a student in order to participate in an internship?

I often wondered about this prerequisite myself especially when I offered to intern and was turned down due to my non-student status.  Once I became a recruiter, I realized that the main reason companies request this (especially in the entertainment industry) is to automatically weed out a group of people they believe may not commit to their internship.  When you are a student and participate in an internship, your school will ask that you and the company sign an agreement (contract) and it will state the minimum amount of hours per week and/or semester that you will be required to contribute to the company in order to obtain x amount of credits/units at your school. It’s basically a win-win situation for all.  You may ask, “Well, wouldn’t I be able to intern even if I am not a student?” On that point, I would advise that you persuade the company you are interested in interning for and convince them that you will be a reliable intern. You can even offer to sign an agreement that either you or they draft. It can be as simple as stating your name, hours per week and amount of weeks that you agree to contribute to the company.