Immigration as Afterlife Feature

 You can't grow food in the underworld. Growth is a feature of life. In the underworld, life is wildly unnatural. All food in the underworld is found on the recently dead, if they manage to cling to something still alive when tip and  fall into hel.

 Nations are attempting to accrue metaphorical sustenance by gathering immigrants and looting them. However, the other nations are also in the underworld, and the immigrants are also already dead, already starved. It's an irrational reflex driven by mindlessly repeating a spiritual resonance. To get sustenance, you need to do better than symbolic immigrants, it has to be genuine living tourists.  

 The only reliable source of food is the pockets of underworld travellers. The living need to carry preserved rations to survive a trip through the sterile land of the dead. However, the living fight back, and the dead are weak...

 The dead can try to resist the spiritual pressure, but it's unsustainable. The dead accrue a karmic debt simply by existing, they can't afford even more debt. To change their situation, the dead first have to be alive, so they can act...