Do you understand that this is Fallout? A game based on 1950's atomic paranoia, which often depicted nuclear was as destroying the world forever? Radiation doesn't work the same in Fallout like it does the real world, never has, hence things like mutant animals, and ghouls. That was always the whole point according to Tim Cain. And even Feargus Urquhart described a possible Fallout: LA game as "the Walking Dead meets Fallout, due to all the radiation". Even one of the NCR's largest cities, large enough it became one of the 5 founding states, is supposed to be infested with feral ghouls and radiation.