Absolutely yes - a lot of nonfiction books that are intended to be a deep dive into a particular topic written by experts are like this, and I think it's clearly because they need to hit a page count as you've suggested.
I just finished a book called Arbitrary Lines, about land zoning in the US. I was looking for a really deep dive into the history of zoning and how it ended up in its current state, or perhaps comparative analysis of different zoning policies. In reality, the book was maybe 25% technical/historical information about zoning and 75% the author going off about how zoning is unfair and leads to inequality. That's all fine, but I was picking up the book because I already have a clear understanding that zoning is the source of problems and wanted to understand how we got to where we are (and maybe learn about what the expected benefits of the existing zoning rules are that got them implemented, which the author didn't even pretend to be interested in because he's totally anti-zoning).
In any case, this is all to say that I strong recommend two things. First, skim! You don't actually have to read the whole book. I'm currently reading a book called Limitless, which is about the Fed's actions during the early days of the pandemic. It started with some history of the Fed, which makes sense in context, but I've already read about the history of the Fed, so I just read initial paragraphs of chapters and initial sentences of paragraphs to make sure I wasn't missing anything important by skipping it. Second, be willing to put down books. It took me a while to be okay with this, but at the end of the day you only have so much reading time in your life, and there's no shame in setting down a book that's disappointing and moving on to something else.
In terms of finding books, if you're looking for this kind of nonfiction, I like recommendations from experts. I really like Bill Gates' reading list. NPR Best Books (https://apps.npr.org/best-books) as well.