(The child who is going to grow up to be a real pianist truly ENJOYS his/her piano lessons - and that is why he/she does all the scales, etc, with enjoyment [probably because he/she pictures the future skill when it is developed]. The child who is NOT going to become a competent pianist is bored by or actively hates piano lessons. (I speak from personal experience, as I was just such a child who hated his piano lessons AND the practice!)
That's all my point is. Most students hate piano lessons. Are you claiming that this is due to piano teachers? If not, then why claim that math teachers make students hate math?