Yeah, on Android you use DAV5x or something for syncing, and then another app for calendar (I use Etar). I think DAV5x also acts as an intermediate for smartwatches for calendar notifications, but haven’t verified this, it’s just a hunch of mine. I think it’s probably for ease of development, so the same CalDAV thing doesn’t have to be redone over and over again.

As a previous iPhone user, I liked that it was in settings (I did not like, however, that I wasn’t able to set up Radicale on my iPhone at all since I didn’t have HTTPS with my laptop server. I guess something something security no options for you. If it worked for you that’s great! Working things are good)