That's a tough commute to school. The kid isn't just taking a train. The kid has to take the Yamanote line, one of Tokyo's busiest lines, and change at Shinjuku station, the world's busiest transport hub. Japan has very low speed limits in dense areas: 40km/h in cities, 30km/h on side streets. That reduces the risk to pedestrians a lot.
Japan also has two things the USA doesn't: High density, resulting in low walking distances between important points; and a very good public transit system, reducing walking distances even more. Both of these contribute a lot to minimizing child/car interaction, in addition to the strict traffic laws.
sorry but kids walk a pretty good distance to school. high density doesn't mean school is down the block, plus some school is based on your skill level not your distance from, so you may be in the upper public school across town because you did so well. What Japan has is a lot more responsibility and empathy at crosswalks. They are used to traffic and respectful of others. Selfishness leads to speeding, mistakes which leads to crashes.