It seems that many people are unaware of the differences between bribes and rewards. Not to my knowledge. Neither is completing homework and chores, or behaving appropriately in class. Looking at the definition, these two should never be confused. They are at opposite ends of a continuum.
Bribes encourage bad or illegal behavior.
Rewards are the exact opposite. These might be considered bribes because they are offered before the behavior. Critics are correct that this practice rarely works. If the positive reinforcement precedes the behavior, there is no recourse if the children don't hold up their end of the bargain. They were already awarded the free time.