My brother claimed to know the story of La Llorona and recounted it here:

“In some poor part of Mexico, supposedly some lady went crazy and drowned her kids or killed them somehow.

And now she goes around crying ‘n shit about her kids.

And if she sees a little kid being bad or something… bad to parents, she snatches them away and takes them. And then she probably does to them what she did to her kids.”

I’ve heard many versions of this tale. In some she is intended to be more believable than in others. In this one she is a less developed character so her actions are given more attention than her motives. She punishes children that are out of their parents’ control without personal reasons. This suggests to the children that their transgressions are so grave they will not go unnoticed and are the concern of greater powers. Parents tell their children this tale to instill a fear in children they hope will make them more obedient.