Revenge movies only work if...
...if the bad guys do something horrible to the victim. Yes, they kidnapped her, but she easily escaped. She then spent the majority of the movie running away from them...not running toward them to get her revenge. Including the time when she say down for cake and coffee with the woman neighbor instead of insisting on calling 9-1-1.
She eventually seeks revenge because she found our they killed her sister, but this was with about 5 minutes left in the film. Why not reveal that much sooner?