What hurts so much about this story --and what I think the filmmaker did so well at conveying-- is that it's not just a case of bad luck for one particular person. It's bad luck compounded by that person's particular class status within the society she lives in.
An accident like this would have been tragic enough but add to the tragedy of random luck the tragedy of a grossly inequitable society filled with racism and classism and the sum is just too much. I can't help but think that if Rosa had been someone like me (white middle class) the result would have been vastly different.
You cannot leave this movie without being outraged at the overwhelming cruelty of a system that failed and continues to fail.
