The kids were supposed to be in school. Pretty hard for 12-year olds to juggle that schedule.
Johnston is mostly a very upscale area. Somebody did indeed notice the kids were alone after the first day.
The charges are all misdemeanors.
When I was twelve I was quite able to get myself and my eight year old sister to school if my parents went to work early.
I didn’t know that was considered an unusual skill.