Last year, when my youngest was 6 and in first grade, our neighbors asked what I thought about letting their son (same age, younger by two weeks) walk home alone. I flat out told them I thought it was crazy and we still get our kids off the bus...our oldest is in 6th grade and someone meets her daily. Either way...this year, he is getting off alone. It annoys the heck out of me, but I stand at my door and watch him walk the extra 5 houses to his - no matter what the weather. The only time they come get him is if it's raining.
He also never wears a coat, but because we are friends with this family, I know it's because he is ALWAYS hot. Literally, this boy sweats more than a grown man. He is always hot and rarely puts a jacket on. Not my problem. Not my bill if he gets sick, not my leave if they have to stay home to care for him, not my time at the doctor/pharmacy. It's their call...so they get to do what they want.
People raise their kids how they want to, and we don't get a say in it. Please just leave them alone. Do NOT call CPS on them, don't report them again. They are raising him how they want to. Unless he shows up with bruises all over or tells you there is no food and he's hungry, let them parent.