The honest version of most AI deployments is not "the AI decides" but "the AI handles the volume, and a person handles the judgement calls." Human-in-the-loop is the design pattern that makes that split explicit, rather than pretending a system is fully autonomous when it is really relying on someone quietly checking its work.
How it actually gets built, not just claimed
In a working system this usually means a confidence threshold: high-confidence outputs flow straight through, low-confidence ones route to a reviewer automatically, and the routing decision itself is logged. Every serious IDP deployment runs on exactly this pattern, and a vendor who claims their system needs zero human review is either describing a narrow single-format use case or overselling what it actually does.
Where it matters most
Regulated decisions, credit, compliance, KYC, contract risk, are where this stops being optional. The technology stack for production agentic systems centres on defined checkpoints for exactly this reason: too few checkpoints and errors compound before anyone notices; too many and the automation stops adding real value.