I agree with you 100%, and my reply nearly included that if one believes in free markets then one can't call it unethical. The only thing that gives me pause is that interns are often young and inexperienced and may not realize that their skills have value. While the burden of such education is on the interns (intern candidates, young 'uns, hackstars, whatever), it still seems morally questionable to me for companies to intentionally exploit that inexperience.