

Kinda correct, it was a ratings issue. The problem was that we didn’t have an 18+ rating for video games - if your game was deemed 18+ then you couldn’t sell it here. Sex, depictions of drug use, and a couple of other things I can’t remember right now are reasons for an instant 18+ rating.
Bethesda got told they couldn’t sell it to anyone in Australia, so they compromised to drugs that didn’t actually exist.
Left 4 Dead had something similar with the gore; if I remember correctly, L4D rating submission referred to the zombies as “monsters” (or something) and passed while L4D2 referred to the zombies as “infected people”… because they were now people, our ratings board shit the bed protected the children and gave it 18+ until they removed the bodies and gore. It was patched back in by Valve when we got an 18+ rating.
South Park: The Stick of Truth has/had some good censored scenes about this, graphically describing Randy being probed by an alien while the graphic of a koala sits in the background. These were patched out too I think (or I downloaded a mod).
We still have people like these lobbying against porn on Steam, but the overall situation got a lot better when we got an 18+ rating.
The name changes go back to Fallout 3 (at least, I can’t recall if FO1 & FO2 had the same drama).
By the time of Fallout 4, names like Med-X (morphine), Rad-Away (iodine), Brawno (amphetamine? I can’t remember) were well and truly bedded in, and suited the aesthetic. Why change it at that point? They’ve created names that suit the aesthetic better than the actual drug names.
I was in my mid/late 20s when this was all going down. I grey imported the MK reboot so I could play, had a copy of Manhunt, and others. The Fallout drug names were a result of the lack of 18+ rating and trying to comply with MA15.
https://arstechnica.com/gaming/2008/07/fallout-3-cant-get-a-rating-in-australia/
https://www.smh.com.au/technology/fallout-continues-from-ban-on-game-20080715-gdsma8.html
https://www.gameshub.com/news/features/australian-classification-law-video-games-2646457/