My answer to a question in Quora

At the administrative level, I think it was one of the legacies of Andrey Bubnov, People’s Commisary for Education in 1930’s: commisionning and publishing hard textbooks was a way of setting standards which could not be dilluted in provincial universities and schools. Bubnov’s post was a demotion: prior to that, he was Head of the Main Political Directorate of the Red Army, he was in charge of training of the Army, and, what matters for this thread, educating the officers, setting up military academies and providing them with textbooks. Presence of “canonical” textbooks sets standards obvious not only to teachers but also to students. In England, mathematics in schools and in universities is taught without textbooks (one of the reasons is that university level textbooks are too expensive) , with pretty damaging consequences for the state of education.

The most complete answer from a discussion is the following from Alex Sergeev, PhD in Physics:

As I understand from reading comments, the [discussion is] not school textbooks, but university textbooks, in particular Landau-Lifshitz was mentioned. In such case, I have to disagree with most answers presented.

Firstly, yes, they are indeed noticeably more hardcore than courses of a similar level in the US. Enough to compare two classic courses: Landau-Lifshitz and Feynman Lectures (which are, in turn, not really a walk in a park either, there are plenty of friendlier books). Same can be said about mathematical analysis books which I encountered. Soviet textbooks just go straight to the point and throw lots of definitions and formulas at you, without any preparation. The US textbooks try to explain simple things in more detail, and increase the complexity as they progress.

The reason for it, I think, is the difference in education systems. In the US, the point of education system is to teach students, as well as possible. In the USSR, the point was to get rid of weaker students and have only very good ones left, who would understand the subject no matter how hardcore the approach to it is. It might be more psychological rather than intentional, but in Soviet times it was a general sentiment: if you can’t do it straight-away, you are simply not good enough and should do something else. The US system tries to improve students and then select the best, the Soviet system tried to select the best and then improve them. The US system tries to make geniuses out of average students, the Soviet system tried to select geniuses disregarding average students. I might be a bit too categorical with this, but I don’t think it is too far from truth. Another possible reason, stemming from the above is a lack of competition. In the US, the education system is adapting to students’ need, if the books are not teaching good enough they get replaced or amended. In the USSR, the textbooks were centrally selected and approved, and students had to adapt to whatever they were given.

Edit: I also have just recalled this phrase very widely circulated during Soviet times: “We don’t have irreplaceable people”. (It actually originated much earlier, and was used by Woodrow Wilson, but is widely assigned to Stalin, who in fact never said anything like that. I also believe that the connotation was intended to be different.) This phrase, however, well demonstrates the psychology of Soviet system. No one cared if you fail, there’ll be another person who’d take your place. In the US, if student is struggling, it is partially a teacher’s fault; in the USSR, it is 100% student’s fault.