Telling a story inherently has bias because of perspective and the way the story is told.
Every screenwriter worships at the altar of Robert Towne, and we do.
Even the best documentary has somebody's bias.
When I tell people I'm a screenwriter, people think I'm automatically artistic, but hell no. I like being part of a team, and I like having a skill that the team values. It's like laying bricks, and I try to be the best bricklayer I can.
Screenwriting, as a whole, tends to be more objective. In a novel, you can have chapters of stream-of-consciousness writing that add depth to the plot and characters. Film doesn't allow for that by its nature, at least in the long form.
Anytime you tell a story about someone who has made a hard, fast decision, if you're telling an honest story, over time that hard, fast decision is probably gonna become opaque, and they are going to see the downsides of the choices they've made.