Which is cheaper:

1. having a human expert creating every answer

or

2. having an expert check 10 answers each of which have a 90% chance of being right and then manually redoing the one which was wrong

Now add a complications that:

• option 1 also isn't 100% correct

• nobody knows which things in option 2 are correlated or not and if those are or aren't correlated with human errors so we might be systematically unable to even recognise the errors

• even if we could, humans not only get lazy without practice but also get bored if the work is too easy, so a short-term study in efficiency changes doesn't tell you things like "after 2 years you get mass resignations by the competent doctors, while the incompetent just say 'LGTM' to all the AI answers"