As I've mentioned before, one of my students is studying Criminal Justice at a college on a military base. She's taking a class in Juvenile Justice and has the same sort of textbook that you use at most colleges. It's extremely difficult for her to understand in large part because of the specialized vocabulary but that's not the hardest part for her. She can look up random words and get translations.
The harder part for her is that she has issues de-scrambling the sort of language that textbook writers feel obliged to use. Sometimes, the grammar in the sentences is contorted such that you have to read it more than once to understand the point. This is often the case even for native speakers. One of the sentences which she had particular difficulty with was something which said something along the lines of 'a framework from which to study (a topic)'. I can't recall the rest of the sentence, unfortunately, but it was clear that the way in which the sentence was written was awkward (though grammatically correct) in order to avoid the use of "I" or "we".
When I was in college, I remember specifically being told that one was never to use "I" or "we" in academic writing. I don't know why that was the case but, to this day, when I write anything, it's in the back of my mind that I should try to avoid using such types of sentences.
Besides the tendency of textbooks to use contorted grammatical structures, they also seem to go out of their way to use uncommon vocabulary. I'm no slouch in the vocabulary department and my husband is even less of a slouch than me but the book I'm currently reading, Adaptation and Human Behavior, often has us both clicking our way over to dictionary.com. I'm reading this book, incidentally, as a nice little palate cleanser between novels though the number of $20 words is really clogging up the mental pipes as I try to slog through the book.
I'm not talking about jargon. In fact, I understand the jargon pretty well having studied psychology and appreciate the need to use a word like "phenotype" because it saves the writer from using multiple words to describe "body type" and it fits in with the phenotypical body descriptions (ectomorphic, mesomorphic, endomorphic) aka somatotypes. Now, wasn't that far more confusing than saying body types which tend to be thin, muscular, and fat?
At any rate, I don't take issue with this type of jargon because I know that the ideas underlying them are more sophisticated than "thin"," fat", and "muscular". In some cases, using simpler words undermines the meaning the writing is trying to get across. In other cases, however, it seems to have little to do with conveying words which carry more depth of meaning than more commonly-used vocabulary. For instance, what is the point of using a word like "adduce" instead of "cited"? There is no added nuance carried by "adduce" over "cite". It's just a less commonly-used word.
I'm never sure if academics sit down with a thesaurus and find new and uncommon words in an attempt to appear more sophisticated or to use words that are less common to spice up their dry content, or if they use these words because their exposure to vocabulary is extraordinary. Either way, for both my student and I, this is sometimes a pain in the ass.