I don't know the legality of this practice but it's a common practice in salons too. At least it was way back in the day in another city I lived at the time. I "tried out" at multiple salons that strung me along and never hired me and never paid me. I suspect they do it knowing full well it's free labor without ever intending to hire anyone. It's super shitty and exploitative. I'm sorry for your friend. Maybe look up the state labor board?