Just because someone wants to avoid being traced does not mean they are involved in criminal acts. This is along the same lines as "If you have nothing to hide..."
By your analogy, because some people use cars to commit crimes, then all people use cars to commit crimes, and therefore, not only the owners of Volkswagen, but the car dealers that sell Volkswagen cars (they provide the vehicle...) are just as liable as the Tor node operator.
I guess the O.P. of this particular thread would surmise you are a "criminal" attorney.