I worked at the Apple 5th avenue retail store until April, and there is a document that has to be signed acknowledging that you could lose all your data. That said, it's usually framed as a "this probably won't happen, but just in case"
Back before Best Buy had the "Geeksquad", we had the exact same type of form. And we framed it the same way, actually had to almost underplay that bad things could happen.
