Galilee isn’t in Judah.Ehrman is citing sources that are 20 years old.
The thing about historical scholarship is that conclusions change as new information and methods become available
Study confirms widespread literacy in biblical-period kingdom of Judah"many of the inhabitants of the kingdom of Judah during that period were able to read and write, with literacy not reserved as an exclusive domain in the hands of a few royal scribes."
I started to suspect that literacy in the Roman Empire wasn't just limited to 3 percent of the elites when I saw a lecture about graffiti discovered in ancient Roman cities, much of which was bawdy and even pornographic in nature, just what you would expect from working people, merchants, skilled laborers
There was no military presence there.
Your reference is mundane OT, stuff. Transaction records and the such. In Hebrew, not Greek.
And being able to merely read and write doesn’t mean one could author a gospel. In Greek, no less.
Keep grasping