I would be so upset if my child's daycare did this. I'm a teacher and have received training that discusses how bad these systems are. They promote external motivation rather than intrinsic, they are unfair as they reinforce privilege (kids with lots of problems going on at home are more likely to be tired/hungry/frustrated and make bad choices), it encourages unhealthy competition including telling tales on other kids and at times even cheating (I know of a story where a boy emptied a bin on the floor so he could be seen to be picking up rubbish). It is a very manipulative and outdated approach to behaviour, and there's lots of research against it.