To be honest, the Naruto world vaguely reminds me of ancient Sparta.
When a child was born in Sparta, they were bathed in wine. Assuming they survived, they were taken before the elders to determine their worth. If they were sick or weak, they were left on the mountain to be exposed or die, but a lot of times slaves or serfs, called Helots, would adopt them. If they were worthy, they were given military training at an early age.
In Sparta, the warriors were given their shield by their spouse and told, "With this, or Upon it", similar to the headbands the Naruto Ninja wear. Basically, in Sparta, you either returned victorious or dead. anything else was considered treason and was punishible by death or banishment.
Roughly, that's Kishimoto's world, only he doesn't stick to his guns on that. All those missing-nin out there and no one's doing a thing about them.