No war was fought on the californian mainland. (if you count out hundreds of nukes exploding
)
Oh snap

Well, we can speculate vaults and military bases were scavenged xD
How exactly is that "unfalloutistic"? There were some robots in fo1 and fo2, centered around previous military bases with a few here and there, that doesn't mean that robots should be common where every third or fourth wastelander has one following them around.
Just like Arroyo didnt say there were many tribes, neither you could not see any human NPC with mutant slaves, but could see robodogs at NCR/Navarro, repair bot in NCR but that doesnt mean to you they were operational and commonly used by inteligentsia. Oh wait what we have currently in fonline? 5 mutie mercs? Well, it completely fits to your thinking (not playing atm, heard they were some changes to mutant armies xD)