Also can't forgot Brazos,Lubbock, and until 2018 Hays County in Texas. I think part of it is just there isn't any motivation for these students to vote.
That’s part of it. I think the prior posters in this thread hit the nail on the head in that the schools are socially structured in a way that attracts more conservative folks, particularly Greek heavy schools like Ole Miss and Alabama. I will note though that almost all of the college counties in these southern states have reacted quite negatively to the Trumpist turn in the party and that’s pretty evident in some of the violent left swings you see in recent elections in these traditionally conservative areas: Hays, TX; Brazos, TX; Tuscaloosa, AL; Lee, AL; Lafayette, MS to name the red ones, not to mention already liberal southern college counties that have only trended further left like Travis, Alachua, Albemarle/Charlottesville, Boone (not really southern I know)