I don't think unpaid internships should be illegal. I worked in a lot of unpaid internships early in my career, and it helped me build my skill set. In some cases, a position didn't exist, I just asked if I could work for free to learn. Those are jobs I wouldn't have had, much to my detriment, if the employer feared being sued or fined for not paying me.
I think this is particularly important if you're trying to learn how to run a company rather than learn specific job skills.
I think this is particularly important if you're trying to learn how to run a company rather than learn specific job skills.