RAGE.
Yeah, the game says the Authority is bad and the Resistance is good, but there's really no justification for it besides "because I said so".
When you break into an Authority prison to rescue a Resistance member, he's healthy, looks well fed, and doesn't look like he was tortured or mistreated. He was certainly healthy enough to start fighting right when you saved him.
When the Authority takes over Wellspring, they don't take anyone's property, don't hurt anyone, and don't disrupt any business. They do take the mayor, but he was jerking you around for his own needs, so going by how they treated our resistance friend, he'll just be in jail.
They are hostile, but that's because the only times you encounter them is when you're invading their areas. They only aggressively pursue you after you invade their areas and murder their soldiers. The character you play is kind of a dick.
I have seen no evidence to suggest that the Authority are really bad. There's rumors, but they're just rumors. Some say they're behind the mutants. Why would they make mutants? What goals would that accomplish? Are they doing it for kicks? To combat the large bandit population? What is the purpose of that?
Yeah they had Wellspring prisoners, but what did those prisoners do? For all we know they murdered Authority members "just because", kind of like what you do.
Yeah Cross set his ark to release early so he can seize society. But we're never told why he did it. Was he a mego-maniac? Did he just think he was doing the right thing and just wanted to help? The other Ark survivors join up with him, so maybe he's doing something right. We're told they're "taken" by the Authority. But, how is that much different than what you went through? You were taken by John Goodman who then tells you to do menial tasks for him and to kill people.
I just think it'd be interesting to hear the Authority's side of the story. Because based on what I've seen, they don't seem that bad.