I am a student at online MS from Georgia Tech and a large number of TAs is pretty usual there too.

Incidentally right now I am taking the AI course there and the assignments submission and checking is automated to the core. There are a few hiccups though but the team of TAs is super responsive and working through it.

I think these are the things that should be automated by default in most courseworks as it frees up time for more important things. I see we have a lot of office hours in my course and I can basically jump to any running hangout based office-hour within few hours from the time I have a question.