The concept can certainly be introduced via tee work, but this particular issue occurs because she is attempting to level to the ball AS she is "reading the pitch". Girls with this issue can learn to perform good healthy tee swings ... they can perform high-tee swings until the cows come home ... but since they are not "reading the pitch" as they swing, they haven't solved the real issue ... and the real issue is with the leveling process as one "reads the pitch".
Tee swings are often overdone to solve issues. Tee swings do have a place ... but to truly develop a hitter, and to get them through issues like this, you need to go beyond tee swings and develop the swing while the ball is pitched.
We're not far apart, I think. Part of the "leveling process" is related to a movement pattern where the barrel is dropped flat behind the shoulder before the swing is launched (DBSF). Learning how to turn the barrel properly requires re-programming the body to move in a different pattern of movements. Tee work can be a big help (IMO) in focusing on programming the new movement pattern without the pressure of adapting to pitch location. I definitely agree that tee work can be - and often is - overdone.