Researchers have found that Japan has exceptionally high rates (98.3 per cent) of walking or biking to school among children compared with other similar-income countries.
7 Reasons Why Japanese Children Have the Longest, Healthiest Lives
Naomi Moriyama

I found this culture of letting the children even at a young age to walk going to school everyday helps them to developed a sense of responsibility by not being dependent from their parents to take them to school or ride in a school bus.
Parents trust their kids and the environment, and nothing could harm them because it is safe to walk even without the presence of an adult. Here, it would be impossible to do that so they have to ride the bus or in the comfort of their car.