It has always been assumed that they are, whether or not it's true. As they don't have the fully developed reasoning abilities to tell if something will have long term consequences. That's why there's crossing guards. It's hard to get a group of kids to stand at one intersection and wait for a light to turn and then take into account people turning or maybe speeding to make the yellow.

The child safety comes from the crossing guards in the morning and afternoon when the vast majority of kids are outside. The camera in front of McCoy still goes off after 5pm if I'm not mistaken.