I got this email last month from the parent who was hoping I'd take his son as a transfer student. His son is twelve years old.
There are a couple of reasons we would like to make a change. His current teacher chooses pieces for him from the core classical repertory, and challenging ones -- not quite beyond him, but requiring months of work. Jimmy keeps at it and brings his pieces to a pretty good level, but it's not as interesting for him as it could be. I've occasionally asked his teacher for some lighter choices, to give Jimmy some easier successes and a broader musical diet. (He loves Ludovico Einaudi and Joe Hisaishi, but his teacher wouldn't want to work on that music with him.)
I'd like to say that these emails are rare, but they're not. I get them all the time. It seems like teachers around the world are busy teaching students things that they're "supposed to" be teaching, while neglecting to teach their students pieces they'd love to play.
Out of frustration with this sort of thinking, I made this video. I hope you enjoy it.