WikiSummaries is not related to WikiAnswers, so we cannot speak for them as to reasons why or why not. I can take a guess at saying, simply because no one has written one yet. Like WikiAnswers, it is a volunteer site. You could always read the book and write one for them to help out the next guy. The link to do so is listed below.
the mom because not(hasnt) not(double negative has) not(hasnt) person that has not (has [double negative]) not (hasnt) set foot on the moon
it hasnt
hasnt
He hasnt.
he hasnt
he hasnt
it hasnt
she hasnt died!
She hasnt yet
she hasnt yet ;)
it hasnt
it hasnt i hope