I’m guessing a treaty wasn’t the reason they didn’t resort to large scale cannibalism, though. I’m guessing they didn’t resort to cannibalism because it is, you know,
cannibalism.
Cannibalism (other than the ritual kind) is rare. And generally only seen when all other resources have been exhausted.
Like say being at the top of a mountain range in winter where there is nothing else to eat. Or on a lifeboat, same thing.
Before people go that route, there are a great many other sources of food. From horses, dogs, cats, sparrows, rodents, amphibians, etc. You literally have to exhaust all other sources people that is what you are stuck with.
And it seems to be less of a problem with those in the military, because they are the military. More disciplined than the common civilian, and knowing that there is yet another legal system that will make shore work of them. The "Brothers in Arms" tends to look out for themselves, far more than the common civilian I think.
I read a biography many years ago, forget the name and author. But it was by a civilian survivor of the Great Patriotic War. One of the neighbors was selling "rat meat", and it was discovered it was really the flesh of dead German soldiers. He was not eating it, but selling it.
When the neighbors found out, they killed him and fed him to dogs. So even if true, this would be unwilling cannibalism.
And interestingly almost all of the Fallout games have similar storylines. Cannibalism is generally not part of the game, but in several sections you have individuals selling human flesh, but not consuming it themselves. From Iguana Bob in the original game, to Andale and the "Strange Meat Pies" of Fallout 3. The White Glove Society of Fallout New Vegas. And in 4 you have Longneck Lukowski who sells tinned meat made of irradiated humans. As well as "Mystery Jerky", made of human meat in the Nuka-World expansion.