That is probably not that intentionally. That is just a result of my own observations.
As of culture:
Canadian mother: John, you are so smart, why you cannot solve this quiz?
Russian mother: Ivan, why you cannot solve this quiz, are you stupid?
Anecdotic exaggeration of course, but there is definitely something in it.
So, for example the first ~2.5 years (out of 5.5) of my CS degree were mostly about some pretty brutal math units, each with an exam. There was also other stuff from entry level CS to physics to some token humanity courses but that was easy for most. If you were inclined/smart/persistent enough to master the math (or, sadly, as some did that being Russia - not sure how prevalent that was in the USSR - bribe your way when you failed), you could continue to the easier more fun later years where you actually studied some CS. A considerable number of people transferred or dropped out.
From what I understand, in the US, the same course on, say, Introduction to Calculus, can be attended by people who are learning to be MDs, chemical engineers, accountants and mathematicians because there is no fixed curriculum and everyone can pick up that course. So the textbooks and courses need to be as accessible as possible to accommodate a wide range of aptitudes.
In Russia/USSR, at least till 90s (don't know if it's still true since there had been a movement to "westernize" education) you enrolled into a major, not a school, and the whole class had the same curriculum for the first two years with some specialization starting on the third year (the whole program is 5-6 years). So students with the same major go to the same courses, which are not shared with any other majors. In this system Introduction to Calculus for mathematicians will be very different from the course with the same name for sociologists and does not have to be as accessible for people who do not really care about strictness of proofs, structure and other "mathy" stuff.
in publicly funded systems students cost money, so there's an incentive to control cost. In privately-funded systems, students make money (in particular with universal loans), so everyone's a paying customer and nobody turns those away.
Germany has roughly half the university graduation rate compared to the US, and this is the same reason why the US gives you 8 late-stage cancer treatments and the NHS gives you 2, or why sometimes you don't get the super expensive medicine you want.
(I grew up and went to college in the Eastern Bloc.)
Further, reasoning that American schools get money might hold true for tuition based schools, but my understanding is that large percentage of pre-university mathematics courses are taught for free. So again, doesn’t make sense to me, because if that was the case, all schools would charge and majority of students would finish university to maximize the profits, and again, this does not match my understanding of how things work.
Are you saying that in Russia, since the education was free that the goal of the textbooks was to make it hard to want to stay in school, if so, to me, seems like it’s unlikely, but possible.
Putting aside non-Russian textbooks, what are you saying the intended reasoning of the textbook form was as it relates to Russian culture?