In the yesteryears girls were held to different standards than the boys. But lately, parents see no difference between a boy and girl.

The reason mothers may be harder on the girls could be because she has multiple roles to fulfil compared to a man. Men are mainly seen as bread winners. But girls have put on multiple hats- daughter, sister, wife, mother, and nowadays career woman. It's ain't easy managing a home and work. So unless she has been well equipped or "toughened" up she might not be able to meet the challenges. Failure is not an option mothers would like their daughters to face.