One thing in common both the Fallout universe and the Real World have in common is WW2 ending when nukes were dropped on Hiroshima and Nagasaki. In both cases, those bombs created ZERO ghouls. @200-400,000 people killed outright. So, that means the rate at which people become ghoulified is less than 1 in 400,000. Now, ghouls are described as, "Humans that have received an ungodly amount of radiation." (However much "ungodly" amounts to.)
MANY non-feral ghouls that player characters encounter in FO3, FONV, and FO4 relate that they became ghoulified when the war started, now 210 years in the past. If ALL ghouls share that in common, what then would the rate of ghoulification amount to? Assuming the USA population in 2077 amounted to, say, 500 million, and roughly half of them (overestimate) were caught in nuclear blasts across North America, how many ghouls were likely made that day? Using Hiroshima and Nagasaki as benchmarks, one would expect no more than @50, spread across the continent. But using FO3, FONV, and FO4 as ghoul population samples, they suggest that across North America, there would be literally hundreds of thousands of ghouls still remaining after 210 years. After 210 years of being killed on sight by any sentient beings they encounter. The attrition is so harsh, to have the kinds of ghoul populations that we see in FO3, FONV. and FO4, the initial ghoul population would have had to have been in the millions.
It seems to me that Bethesda needs a deeper explanation of what creates ghouls than "People that have taken an ungodly amount of radiation." Something like ther had been biowarfare bombs mixed in with the nukes, the combination of which unexpectedly created long-lived ghouls instead of irradiated diseased corpses.