I chime with this sentiment. The biggest issue in non-fiction books that I have is this - lack of a progress indicator. If it's a biography or an autobiography for example - I intuitively know the progress and this builds some sort of a curiosity to complete the book. In fiction, this is simulated by the story telling. You are almost always eager to find out what next.

In non fiction however, the lack of progress indicator combined with fillers totally takes away the what next phenomenon. On top of this, most non-fiction books try to convey the core of the meaning in repetitive language. Probably there is some science to this. The more you find repeated words sprinkled across, the more they tend to stick in your head. Apparently something that advertisers and marketers use all the time. So may be that's what drives this repetition and filler materials. I've seen this pattern in quite a few non-fiction books. Hooked, Deep Work, Grit etc.

Which is why I think, it's incredibly hard to pick a reading habit if you start with non fiction books. Also I don't think developing a reading habit with fiction will lead to a non fiction reading habit. Personal anecdote, I used to devour fiction as a teenager and in my early 20s. I remember reading Partner by John Grisham in one sitting, without even getting up to eat. Now I can hardly muster the energy to finish a book. I mean, I can but it's no longer that easy.