For me, it was relatively strict parents sending me to a relatively strict piano teacher who also was a parent, and that combination can be a force multiplier for a bad time. All of them had similar cultural backgrounds as well, being first generation immigrants from the same country.

mkl's reply described it the way I would have explained it. There is that inherent power dynamic between parents and children that can make it difficult to speak up. In addition, piano teachers teaching children are effectively in a parental role for that time.

That's something to keep in mind for anyone who finds themselves in a position of authority over children, who are still in the early stages of expanding their perspectives of the world they live in.