I would need more info to make a complete decision. Some of it depends on local and state laws. There used to be a law in one part of OH that said a child couldn't babysit until age 14. What that meant was that if a child under 14 was home alone they had to have a sitter. It was nuts. There are a LOT of kids under 14 who can be left home alone. And osme who can't. I also lived in an area with a law that said that under the age of 12 a child could not be left home alonefor ANY length of time UNLESS the 12 yo was BABYSITTING younger siblings. So the kid can't be home alone but can be home iwth other kids to supervise? Sorry, but that was just pure legal idiocy. It was not in OH and it was NOT enforced unless a family left a kid home and the kid burned down the neighborhood. Cause, yeah, that happened and it was the first time in over a decade anyone had enforced that law.
IF the child had walked the route to school WITH an adult a few times, and the child is of normal intelligence without untreated adhd or toher issues, then I think the mom deserves a free dinner at a nice restaurant, an hour of free massage and a spa day for free. Plus some gift cards to bookstores, etc.... It is HARD to raise a kid who thinks rules don't apply to them. Parents doing things like this is what lets them NOT feel they can ignore the rules.
IF the child didn't know the way, as in had not walked that route before, if there were regular problems with kids being molested/abused in public places (like restrooms and fitting rooms - at one point I would not let 10yo Wiz use the men's room if husband wasn't with us because there were at least 2 reports per month of kids being abused when using the restroom/fitting room with-o a parent and these were within 2 miles of our home, not in our entire big city. So no way would my child have walked 2 blocks alone, much less 4 miles. BUT most of the time strangers won't hurt you because THEY DON'T CARE ENOUGH ABOUT YOU. It is the people you know who will hurt you.
In the US the law says that schools MUST provide transportation to school if you live more than 2 miles from the school. PERIOD. I know some states have put shorter distances in, but they don't have to. I probably would not let my child walk it unsupervised at that age. We try to make sure thank you doesn't have to walk the 1/4 mile up to the bus in the mornings, but that is because we live in a rural area with no streetlights and we saw what happened to our daughter when she was walking in the early am. That is the ONLY reason we drive him or walk him iwth a flashlight up to the bus stop.
Why is it that they are so upset over this and in many areas won't do anything if a child is left home alone all night or is covered in bruises, or says Dad hurt him and has all the signs of abuse but no one will even go interview Dad because Dad has "rights"?
This mom needs a GOOD atty and if possible a publicist to spin this in the media. I still say she deserves those rewards I listed because I know a LOT of parents who would just call the kid in sick for the week rather than make them go or drive them.