It's because their manufacturing cycle time is too slow.
The value of Print for learning is to stop time see previous post. The new purpose of education is learning, not time training. The internet/multimedia is for talking and buying, not learning.
That still means lots and lots of versioned and personalized Print.
To get the learning thing to happen for everyone, not just the kids that naturally learn anyway, it means print on the demand of the teacher. Just the right content in the just right media at the just the right time for just the right classroom and just the right student. See Disrupting Class: How Disruptive Innovation will Change the Way the World Learns.
To see how an MPS or a printer/OPM can crack into the education space, see previous post.