It seems there is a Global Shortage of Cannon Fodder.

Military planners are beside themselves with worry, panicked they won't have enough warm bodies to throw in front of the bullets.  The whole concept of an army relies on a commonality of interest and loyalty to inspire the population to want to fight together for something.  The Battle Cry for the Brits as they ran into a hail of bullets was "For King & Country!".  What Gen Z waste-o is going tofeel kinship with #ShitzinPants or Uncle Joe and pride in the cesspool of 21st Century Amerika?

Besides the fact raising a sufficient size army being problematic, with modern weapons systems they would be mowed down as fast as you deploy them.  Nobody would ever get off the beach at Nomandy today.  If Hitler had hypersonic Cruise Missiles, all the landing craft approaching the beach would be blown out of the water before they ever even made the beach.  If Vlad the Impaler wasn't trying to minimize escalation into WWIII, he could easily Carpet Bomb Kiev.

Then there is the REALLY stupid idea of fighting wars with Robot Armies.  WTF will care when the newz comes on the tube "500 American Robots were Killed in Action today fighting 10,000 Chinese Robots who suffered much greater losses.  Over 2500 of the Chinese robots were irreperably damaged.  The Chinese still took Taiwan though, because the remaining 4500 Amerikan Robots malfunctioned."

https://www.vox.com/world-politics/355547/soldiers-shortage-demographics-population-conscription

RE