The headline risk everyone quotes — a recall, a suspended licence — is rare, and because it is rare it is easy to discount. The routine cost is duller and considerably larger: investigation labour, QA oversight on ageing corrective actions, working capital sitting in held batches, and the same problem solved twice. Those are lines a finance function recognises immediately once someone puts them on a page.
The reason they usually are not on a page is that they are distributed. Investigation hours sit in operational labour. Held stock sits in working capital. Rework sits in yield. No single line item says 'cost of poor quality', so the total is never assembled and the quality investment case is argued against zero rather than against the status quo.
Cost also escalates rather than accumulates. An open deviation costs investigation hours. A recurrence costs the same investigation twice. An overdue corrective action costs oversight and management attention. A held batch costs working capital and a customer conversation. An inspection finding costs a remediation programme on a deadline set by a regulator. Each stage moves control of the timeline further away from you, which is the part that should interest a CFO most.
The comparison that matters for capability is not consulting fees against zero. It is fees against the fully loaded cost of carrying the capability in-house: salary and overhead for specialists used a few weeks a year, the recruitment cycle, months to competence, key-person concentration, and the work that silently does not happen while one generalist covers four specialisms.