There is no reason the USA couldn't do the same thing today if we adopted some of the same values and intolerance of crime which the Japanese have, and which we still had back in the days when your grandpa was a pup.
We’d have to go back in time when that was possible. Now, those years or time is long lost. I was in Tokyo for several months and witnessed kids as young as six or seven alone with their book packs on their back traveling on the subways and outside rails.