I'm in my early 30s, and I walked to and from school fairly often growing up in a suburb. My wife is the same age and living in one of the largest cities in the country used to ride the subway to and from school, but basically had the same experience of being able to do it unsupervised for at least some portion of her school years. It's hard for me to imagine what circumstances would lead you to not know anybody who had that option at all.