Why does Laurie's mother miss the first P.T.A. meeting in "Charles"?

In the ironic
short story "," Laurie's mother misses the first P.T.A. meeting because the baby
sister has a cold and the mother stays home with her.

The mother/narrator is
very disappointed because she "wanted passionately" to meet the mother of such a boy
as Charles. For, she is incredulous that such a child can exist. This is, of course, very ironic
since the reader later learns that "Charles" is a fictitious name created by Laurie
for himself.
However, thisis believable because the mother is deluded about Laurie, her
"sweet-voiced tot" who "forgets" to wave good-bye to her on his first day of
school, and who misbehaves constantly at home. Certainly, she never reacts to his speaking
"insolently" or his acts of disrespect to her. Nor does her husband respond to
Charles's insolence when, for instance, the boy "climbs" into his chair at the dinner
table and says to his father, "Hi, Pop, y'old dust mop."

Neither
one of the obtuse parents detect the exaggerations of Laurie about the student
"Charles." Nor do they realize that clearly no child would continue with such behavior
without professional intervention occurring. So, when the mother attends the next P.T.A. meeting
and speaks with Laurie's teacher, she is, indeed, surprised as she finally deduces that she is
the parent of "Charles."