Interesting question. We live on a busy main road, where "idiot" would be a flattering description of many of the drivers. There is a reason why our kids do not go out on their own.
I don't know if children were really safer in Enid Blyton's day, but I think they were perceived as being safer. That was probably the background to the books. I can only add observations to your question Mo, because I don't know the answer either.