I think it's wrong in every way.You, Queenjane, are totally right, imo.
But just because YOUR child can remember, doesnt mean ALL children can remember.
I also think that you are assuming all parents are as involved as you are. Your five yr old only remembers, because you've instilled in him that its important....what if you had alot of other things going on in your life (whether because you were working three jobs, or had six other kids, or because you had issues like drug or alcohol dependancy, or because school issues just werent important to you...), and therefore your child didnt get the support at home to do his homework or remember to bring it in? So that child gets punished because his mother dropped the ball?
I personally think that rewards are often just the flip side of punishments. Imagine being the only five yr old in a class who forgot his assignment, and having to watch all the other kids enjoy their treat. Personally, i dont think thats a very effective way to teach "good habits".....my son will never forget (and he's 11!)when he brought cupcakes into his K class for his birthday, and was told one particular child couldnt have one because he didnt finish his work. It was sad. These are 5 yr olds! If a child is forgetting his homework, the teacher should come up with creative/effective ways to help him remember it (and may include talking to the parent to see if there's an issue at home)....not singling out the child for punishment.
Giving kids SWEETS when they are not going to be brushing their teeth for hours is detrimental to dental health=BAD HABIT
Motivating good behavior with sweets sets up equating sweets with being good=BAD HABIT