It is perhaps challenging to correct and grade essays on any course or discipline. Assignments have different goals and expectations. Generally, no matter how divergent a student’s response is to the prompt, it is still worth some points, unless it is proven to have been plagiarized. Remember that students’ efforts deserve merits.
If you've ever removed red-eye from a photograph, or used a spell checker to correct an essay, then you know how computer software can... well, "enhance" your raw material.
and 30 minutes rather than 2 hours to self-correct an essay