Why doesn't Atticus tell the children about Mrs. Dubose's motives before her death in To Kill a Mockingbird?

Atticus probably felt that Mrs. Dubose's highly private
medical dilemma was none of his children's business. He also may have felt that they
were too young to understand. It is possible that no one else in Maycomb--aside from the
doctor and her housekeeper, Jessie--knew about Mrs. Dubose's morphine addiction or her
desire to kick it. From a professional point of view, Atticus was probably legally bound
to keep such a matter private. He explained to Jem that she had summoned him to make
final preparations for her will, so he was also being paid (unless he performed his tax
for free), and all such matters would have been of a private
nature.