"If violating terms of use is a crime, then private companies across the country get to decide who goes to prison for what, instead of lawmakers."
When these same "private companies" are allowed to commission their own police forces, it can get a lot uglier pretty darn quick, given the close relationship that most police departments have with local prosecutors.
Just recall what MIT police did to Aaron Swartz after he "overused" his library privileges by downloading too many papers from JSTOR, most of which were already in the public domain anyway.