I think the one I see does it to try and bond or so I will see her as good and "on my side" or "not the enemy".
(phrases she has used). Grades, prizes, rewards, and even avoidance of most punishment did not motivate me either. Money doesn't, desire to fit in doesn't, the sole objective of making others happy doesn't. Winning doesn't. Losing doesn't. Disapproval doesn't. Need for certain types of knowledge does. Proving I have that knowledge can but not always. Not if there is pressure from outside to prove I have it. Wanting to be competent does.
Perhaps my mother was right. I am difficult to motivate if not naturally inclined.