Fascinating...
I am a self-admitted grammar nazi as well. Ironic as this should come up. Last night, other half and I got into our first sort-of-argument... over a stupid comma. He is working on his bachelor's degree online, and I was proofreading (and editing heavily) his paper last night. Now, I am not terribly familiar with the "APA style," and ended up looking up several examples to get through it, but could not *believe* that even in a citation, a comma would go outside the quotation marks.
Ultimately, I sort of had to walk away, but we had a good laugh about it afterwards. I think what was mentioned earlier plays a big role. As luck (fate?) would have it, his mother was an alcoholic. He had a very rough childhood, generally unsupported, and barely graduated from high school. He struggles with writing, to be sure. I, on the other hand, came from a family of teachers and higher educators, tested out of all my collegiate English requirements, and admit to cringing at grammatically incorrect texts. I know he uses voice-to-text, and can ascribe most of his errors to that. I, on the other hand, edit mine. Sigh.
Regardless, I'd never really thought about how his childhood impacted his learning, because he's a pretty bright guy and has done quite well for himself, mostly through grit and determination. Food for thought.