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This movie wasn't made to be a blockbuster, so the comparison doesn't work. It made 33 million on an 11 million dollar budget, that's what any movie came hope for, to make twice as much as it was cost to make.
Also it came out in August so it's not relevant at the cinema now.
Also I think that the fact that these are very American problems prevented from none-American audiences feel connected to the subject matter and feel the need to see it at the cinema.