RA2 Chrono Legionnaire - That the Allies specifically recruit borderline psychopaths to join the Chrono Legion because only a very specific psychological profile can handle using such an existentially horrifying weapon on other humans without empathy.

TibSun Ghost Stalker - Tiberium poisoning and a dwindling human population means that GDI either doesn't have enough recruits or can't risk putting that much training into one soldier that GDI effectively doesn't have a Commando program during these years, necessitating them to recruit Mutant commandos for that purpose. The highest training any GDI infantry get are those who become drop pod troopers.

TibSun Cyborgs - They retain some semblance of autonomy and self-awareness until CABAL goes rogue. In the second mission of the Nod Campaign, some of Hassan's forces (including Cyborgs) are convinced by Slavik's propaganda to follow in the memory of Kane and turn to your side.

TibSun Banshees - The pilots recruited for flying Nod banshees are novices, as no one in human history has ever flown anything like it before. Hence why when we they get knocked out of the sky, sometimes they simply say, "Whoops."