In A Long Way from Chicago by Richard Peck, why does Effie Wilcox have to use Grandma's privy?

In Chapter Two, Effie Wilcox has to use Grandma's privy because her own has been destroyed by the Cowgill brothers.

Accordingly, the morning after the Cowgill brothers blow up Grandma's mailbox, Effie Wilcox shows up at Grandma's front door. She requests to use the privy but initially shies away from telling Grandma why she has to do so. Too self-conscious to tell Grandma the truth in front of Mary Alice and Joey, Effie first tries to get Grandma to make the children leave the kitchen. However, Grandma refuses to honor Effie's request.

She tells Effie that Joey and Mary Alice are from Chicago and won't be shocked by anything Effie has to say. Eventually, Effie confesses that the Cowgill brothers had uprooted her privy the night before and had flung the pieces all over her yard. Upon hearing this, Grandma pretends to be shocked that the brothers had uprooted Effie's privy three months before Halloween.

Meanwhile, Effie thinks that town life has gotten so dangerous that she's afraid to live there. She maintains that her only consolation is that she'll get to do a whole lot of praying at the prayer meeting the following night. Meanwhile, Grandma plots to stop the Cowgill brothers from perpetrating further mischief on the people in town.