I find this even in well-respected and oft-recommended but relatively light non-fic outside the self help genre. Sagan's A Demon Haunted World and Cialdini's Influence both struck me as being twice as long as they had any reason to be, but they're nigh-classics in certain circles. It makes me reluctant to read non-fic, which tends either to be very specialized and ultra-dense (i.e. beyond my reach with a reasonable time investment) or fluffy trash.

However, better small-scale (paragraph to paragraph) structure of the text and somewhat higher info-density, or simply being more entertainingly-written, can go a long way. See Graeber's Debt for the former and Fussell's Class for the latter.