[Aenima]

The two scenarios are vastly different in my opinion. Grading multiple choice and short answer questions in parallel is a much simpler task than grading a written essay. The essay is complex human thought, not a formal system as in multiple choice or near formal system as in short answers.

The chemistry and engineering diagram grading scenario is closer to the first cases as well. The diagram is a formal visual representation of the underlying solution. There is less variance in the range of correct-looking diagrams than the written word. If the question was more complex, "Please draw a UML diagram of a complete user authentication system," then a human would have to grade it. There are an infinite amount of ways to design and diagram a solution to an open-ended problem.