I'd counter that certain things are expensive and as technologies change, it opens up the technology to a broader audience, which poor people can write now due to changing affordability in writing due to technological changes. With paper/printing that drives literacy where the cheaper the technologies available are, the greater the population literacy. It for instance would be difficult to have a widely literate population if such population was stuck with using animal skins for paper with books being manually handwritten by educated and trained craftsmen. Products that require significant manual labor and/or space inherently bear a cost regardless of the type of economy involved, like the pyramids of Egypt (or Stonehenge, etc) are inherently expensive even though their construction pre-dates the use of currency.