In a tree built with Precision Tree, there are two blue values at each end node, the top one of which is a probability. Why are so many of these probabilities 0 in the finished tree in Figure 9.9?...

In a tree built with Precision Tree, there are two blue values at each end node, the top one of which is a probability. Why are so many of these probabilities 0 in the finished tree in Figure 9.9? What do the remaining (positive) probabilities represent?