Why did the Spartan women, after the battle, pick up from the battlefield and bury only

Why did the Spartan women, after the battle, pick up from the battlefield and bury only those warriors who were wounded in the chest, and not in the back?

This is due to the educational system that was promoted in Lacedaemon or Sparta. The fact is that only warriors who fought bravely and were killed by the enemy on the battlefield could have been wounded in the chest. But wounds in the back meant that this fighter got cold feet and tried to flee from the battlefield, and then he could be killed there by both enemies and his colleagues, who were extremely harsh towards cowards. It was brought up and tempered from a very young age, because the boys were taken from their mothers for upbringing from the age of 7.