To Live and Die (Not Literally) By the Sticker

This evening my daughter, who is four, was playing teacher.  She handed me a tiny sticker from her sticker collection.  "Here you go, sweetie," she said to me.  "This is for good behavior."  I took it from my "teacher's" fingertip and put it on the back of my hand, as most children do.  At first I thought it was adorable but then, call it a full moon or something in the water it broke my heart a little.  Both of my children, and indeed many of the children I work with, live and die, metaphorically speaking, by the sticker.  These children are fundamentally GOOD children.  Developmentally well-behaved, sweet, and likable.  Really, most children are or strive to be, would you agree?  Yet they fall all over themselves to get a sticker, a marble, or some other small token of good behavior-ness.  All this good behavior...for a sticker?  The Montessori philosophy does not believe in external rewards - all "rewards" should come from inside oneself and while this may be harder for kids to "get", I think it is achievable.  Certainly a child who feels good inside knows that their actions are worth more than a sticker?  Can a person be anti-sticker?  What do you think?  I welcome your musings.