>>21969693All of the songs in her archived one were either Japanese songs (like YOASOBI, Aimer, and Anisongs, most of which I remember others singing, so they obviously have the explicit permissions) or originals (her song, Calli's Bully, etc).
I'm on the outside looking it, but there's been plenty of times where one of them was taking song suggestions or had an idea and looked it up during an unarchived stream, seemed to find it in the software, and then said "oh, but we don't have permissions on that one nevermind".
Don't get me wrong, I'm sure some of them actually ARE basic with their music tastes, or just are zoomers and don't know a whole lot of the songs on the list of the ones they can sing, and don't put in the effort to go learn them, so they stick with the ones that were overplayed on the radio 10 years ago when they were kids.
But, the limited song list is part of the reason some of them don't branch out (Mumei is a great example here).