Your Usenet provider certainly knows what you're downloading. The reason you don't care is because someone sued some Usenet provider in the early 90s, and Usenet providers were deemed "common carriers", not liable for the content they carry. Since downloading copyrighted content is apparently not illegal, it all works out.
Also nice because SSL doesn't tend to get preempted by traffic shaping so you usually get close to the max download rate the ISP says you're paying for.