I recently read a book from one of the children's series that was published long ago. The kids went off for adventures without any adults, and their parents were fine with that. Most of the books written for kids in past decades had the protagonists experience all sorts of things without any grown-ups around.
When I was a kid it was normal for us to go out and play for hours without adult supervision, and sometimes we'd even go for hikes or otherwise leave our own neighborhood, though we had to get permission from our parents.
That probably couldn't happen today. And even if modern kids should be on their own because of an emergency all they'd need to do is pull out their cell phones and help would arrive.
It's becoming more difficult for authors to come up with exciting plots for contemporary stories. Of course there are situations like child abuse, but those topics aren't usually appropriate to show in books for children in the middle grade age group.
That's one reason why lots of historical fiction, Sci-Fi and fantasy books are getting published.
Of course there are a few exceptions, but the authors of those books had to come up with extremely creative ways to get their characters in trouble.
Have you read any good books for kids lately?