Was noticing it with Cinderella tales. And why she hides herself.
The Pop Top 20 version is clear enough -- the stpemother might be dangerous. More so in the variants where she's a witch. But there are a lot of variants where the Cinderella figure ran away and worked as a servant. Sometimes it's just to obey the magical helper, which just pushes it back a step -- especially since that command is more frequent when she says home, not when she's a servant.
Yet another trick to retelling one. . . .