I don't know why people say Fallout radiation is so different.
It has some side effects which aren't real, sure, but the Fallout 1-2 symptoms match real life radiation damage.
Again I point out that Ghouls are not formed in the real world if people get irradiated (every Fallout game ever).
Soda companies do no make radioactive colas in the real world (Fallout 3, 4 and New Vegas) that can be used to make deadly radioactive grenades from, rocket companies do not make toy rockets full of radioactive liquid in the real world (Fallout New Vegas), because those products would kill people and kids in the real world.
Radiation does not stay in the open air and running water so strongly for a century or two (Fallout 1 and Fallout 2 for almost a century and Fallout 3 and 4 for more than two centuries).
In the real world you can expose animals to a nuke's radiation all you want and you won't be getting giant cockroaches, giant ants, giant scorpions, giant flies, giant lizards, giant rats, giant mantises, etc.
I don't believe there are any canon examples of people with lethal doses of radiation being 'expunged', even RadAway has nasty side effects in small doses.
The only people to survive are players, and that one time when a magic syringe saved EnclaveMcDouchebag.
If a doctor in the classic fallout games can rid the player of all the rads for some pocket money, what is preventing him from doing the same to everyone else who has the money and is suffering from radiation?
Also we do see someone suffering from extreme radiation poisoning in Fallout 2, Charlie is sick in his tent and if the player has enough Doctor skill, we will know it is because of advanced radiation poisoning, all we need to heal him is inject him with one radaway and he instantly gets up and is all fine, so radaway does also make radiation vanish from NPCs too.
Effects of radiation poisoning are totally wrong, again in Fallout 1 and 2 all it happens is that the characters lose some SPECIAL points, even if they are at death's doors they can still walk and talk to people, travel miles through a wasteland, etc. In real life it will reach a point where you can't even get up from bed and barely say a word.
Also RadAway does not have any nasty effects in the classic games, nothing bad happens when the player uses radaway, if the player gets addicted to it the only negative that happens is that his radiation resistance is lowered. It doesn't affect his SPECIAL, AP, HP, AC, skills or anything else in any way. The game might say that you have a headache, or lost some hair or that you have stomach pains but since your SPECIAL or anything else doesn't get a penalty then it is not severe enough to be considered "nasty side effects in small doses" (if it said you have headaches and penalized your intelligence, if you have a stomach pain and penalized your constitution, if you have hair loss and penalized your charisma, even if it was just 1 point penalty, then it would be nasty).
Remember that radiation in Fallout universe is how sci-fi authors in the 50's imagined radiation was, it was like a mystical magic force that could be used to explain giant animals and mutated creatures, immortality and super powers, etc.