It isn't mentioned (but is implied), but education is not compulsory with the Daemonrexa. Hence, there will always be many Daemonrexa who weren't educated because they didn't need education. Farmers, miners and such could always make do without education, and could live properly with just an apprenticeship in their craft. However, as they have centuries to live, Daemonrexa would mostly all be eventually educated. The younger ones... not so uniformally.

Also, Hounderhowl, I've finally written far enough to mention the Hel Core. They are the 'Hillmen'.