if you wear yourself out mentally all day as part of your occupation, digging into a "good" book is often too much work.
As anecdata: My wife has a "brainy" occupation and her brilliant sister does not. Correspondingly, my wife has no interest in "brainy" books in her free time whilst her sister is always recommending new 900 page tomes.
I relate to this. My brain is fried after a long day of work, and the last thing I have the energy for is reading something challenging. It’s either light reading, or more often (which I’m a little sad about), watching something.