We need, as parents, to prepare our kids for all aspects of life - no it is not "fair" sometimes, my dds often did fantastic work or helped out other kids who needed a friend etc, but often went "unrewarded".. stuff happens... but when my eldest had a bit of a paddy about it in the first year at school we had a chat....
I told her that she is a good child, she behaves well, she does some fantastic work and that with all the love and support she has at home, she is at an advantage... and she always will be..
that some kids don't have that love and support, that some kids struggle - whether with their temper, their work or their life outside school in general - THOSE are the children that NEED star of the week - the ones who maybe do try harder this week to not hit, to turn up on time, just to be good in class sometimes...
that she doesn't need star of the week to KNOW she is good, because she is told often, that her attitude and hard work are valued by us and her teachers. We reward her good efforts with love, with "well done", with trips out and meals out with family - some kids don't have that advantage and need star of the week to show them that someone has noticed and they are cared about.
So to be honest, beyond that day, "star of the week" never mattered one jot to us..