"So what I told you is true... from a certain point of view."
- Obi-Wan Kenobi.
It's all about perception. No one ever thinks that they're the 'bad guys'. It's a good bet that Tech #3 aboard the Death Star thought that the Rebellion were just a bunch of terrorists and that he never thought he'd be killed just going to work.
Lucas took great pains to make the heroes of the PT ambiguously "good." If he was a skilled writer, it could have been fascinating, but nuance isn't his thing. So he kinda-sorta shows us the seppys might have a legit gripe against the arrogant Jedi and corrupt Senate, but then paints them unequivocally as "evil." Then tells us there are heroes on both sides, just so we remember that the Republic isn't all good. But then all the good guys are on the Republic's team. Hack.