I have a master's in education technology.

There's no "simply put" here. Your position is not obvious, established, or universal and this is not simple.

The biggest speedbump to that is teacher time. Grading and returning worksheets for students is a huge unpaid time sink for teachers.

As you say, like most of any of our current issues, it's not the act of doing something that is the issue, it's the lack of remuneration for doing that thing. Any region would gain an immense amount of more "smart point metrics" (what I choose to refer these scores as) if students had their own personal tutors that helped them along. But that doesn't fit our "profit or perish" economic models.

It's not just compensation grading is a very time intensive process so even if it were paid it eats up either personal time or time they could use preparing lessons or assisting students.