Well, this was confusing. There were two editions of the collected Adventures of Tintin and two different first volumes - this one containing The Adventures of Tintin in the Land of the Soviets and Tintin in Congo.
The other volume starts with Tintin in America, which is contained in volume 2 of the other editions.
So, somehow the editions must have been revised to exclude the first two Tintin stories. I.e. Tintin in the Land of the Soviets and Tintin in Congo.
Having read them, I can understand why: the first Tintin story reads like anti-communist propaganda. The second is packed with colonial racism, and Tintin going big game hunting and thinking nothing of shooting 15 (!) antelopes by mistake.
Oh, dear. I'm glad the world has moved on. Even a little bit.
However, I am not sure that stories should be omitted. Yes they are very offensive, but to omit them is to try and revise the story of Tintin and to deny the historical aspect of them, which is pretty close to denying that that sort of racism existed in cult comic strips.