What I find though when taking notes from a non-academic conference presentation is that I often don’t know what the most salient points or compressed takeaways are in real-time. I don’t end up with a transcript but I do end up with a lot of discard and I’ll take pics of some slides.
Compressing accurately requires understanding what's important.
If you understand it that well already, why are you attending a lecture that covers it?
Truly excellent lecturers can often guide some people to that understanding in a note-friendly amount of time, but oh god, most people are not excellent lecturers. The vast majority that I attended were almost literally just reading from the book in class. Book-structured information isn't at all the same as lecture-structured.
Notes are definitionally lossy. If they weren't lossy, they'd be a transcript.
The act of compressing a lecture into notes helps students learn. Merely transcribing does not imply understanding.