Genre conventions.
A lot or at least some people here seem to complain about this movie either finding it unrealistic or too sadistic for what it does and tries to do etc and how in life yes there are examples and films with DIFFERENT approaches towards such subject have been made.
Life overall of course IS different to movies.
But I kind of wanted to mention that this movie simply abides by its GENRE CONVENTIONS so of course it will deal with the subject matter of rape and then have the victim exact violent revenge on her culprits.
Its not really all that complex or complicated overall.