In a nutshell, here's the difference between civil cases and criminal cases in the US. In a civil case, it is considered to be a person (or party/parties) versus another person and/or parties. This is your typical lawsuit case. In a criminal case, law enforcement seeks to bring criminal charges against a person or persons. The police collect the evidence, detectives process, and typically the district attorney (DA) will actually bring the charges up on behalf of the State.
So long story short, while stealing is indeed a criminal offense, you'll never find a DA willing to take that case, for the flimsy evidence reasons listed all over slashdot anytime stuff like this comes up. As a result, the only option left for a company or corporation like this is a civil trial, via their lawyers.
There's more to it, like how winning in a civil trial is much easier to do generally. For a good example, see the criminal and civil trials of OJ Simpson. In the criminal trial he was found not guilty, but in the civil trial he was found "liable", and had a judgment levied against him by the families of the two murder victims.