If you have your child taught from a qualified teacher, they received professional, accurate and qualified techniques to learn their instrument. Things like posture, breathing, holding the instrument, technique on the instrument all have a bearing on how the instruments sounds when played. If not taught correctly, the child will not perform to his or her best ability. It’s the same as anything in life, unless taught property by a person who is qualified in their field, we cannot expect good results. Music lesson cost parents money so they really do want their child to get the very best outcome from their investment. Also, the child must enjoy this activity. There is no point in a parent paying for an activity and the child hates it.