"I think it's the feeling that a person with no money and no connections, who did the same thing she did, might very well have stood trial for treason."
Jane Fonda was in no way responsible for any decision not to put her on trial. It would have been made by the pro-war authorities, trying to damp down opposition, and wary of what would have been a show trial with lots of publicity.
There was a real possibility they might have decided the other way. And bigger stars than Jane Fonda had had their careers destroyed not that many years previously, for being politically out-of-step.