The Ubiquitous Orphans of Yesteryear
In writing for young people, there’s a long tradition of off-ing the parents. In Nancy Drew, her mother—gone when Nancy was a toddler, with a house-keeper taking her place. In Enid Blyton’s works, kids were always on their own for adventures sans adults (imagine trying to publish that now!?) Orphans have been a tradition: Anne of Green Gables, Heidi, and so many more.
In contemporary books, not so much, and in fact, for picturebooks, they are often included for reasons of “safety.” No more young children off on an adventure, alone with only the family dog! (Alas.)