About 70% of the books I’ve looked at recently in shelves and book stores had specified the typeface the book was set in (some with point size and leading). Most were on the verso of the title-leaf, a few books had colophons. I didn’t take note of this part of book design until just recently, and I haven’t looked so much at books set in English. How common is this?
Apropos: Nearly all the books I looked at were in Sabon or Garamond (mostly unspecific, one in Premier), one was in Adobe Caslon and one in Weiss.