Costs that appear on a statement get argued about. Costs that do not get paid anyway, usually out of the one budget nobody reviews, and the decisions that produce them keep winning on the strength of the numbers that were visible.

Three literatures, one phenomenon

Bastiat (1850) named the structure: the good economist accounts for the effects that are not seen. Economics has since given the unseen three specific names. Ronald Coase (1937) and Oliver Williamson (1975, 1985) established transaction costs — the costs of searching, bargaining, monitoring and enforcing, which are absent from the price and frequently larger than it. Jensen and Meckling (1976) identified agency costs, the sum of monitoring expenditure, bonding expenditure, and residual lossJensen, M. & Meckling, W. (1976). 'Theory of the Firm: Managerial Behavior, Agency Costs and Ownership Structure.' Journal of Financial Economics 3(4). The residual loss is the part that persists after all cost-effective monitoring — a real cost that is by construction never observed as an expenditure. — the last of which is real, unavoidable and by construction never recorded. And procurement research has long measured total cost of ownership (Ellram, 1995), finding acquisition price to be a minority of lifetime cost in most categories.

Why they are not merely overlooked

The omission is not carelessness. Frederick and colleagues (2009) showed that people do not spontaneously consider foregone alternatives when evaluating a purchase, and that simply prompting them to — reminding a buyer that not buying leaves the money available for other things — measurably changes what they choose. If the comparison has to be prompted in a laboratory, it will not happen unprompted in a business, and any process that records only invoiced amounts will systematically favour whichever option pays in the unrecorded currency.

In an owner-operated business that currency is almost always the owner's week. It has no line item in either direction, no approval threshold and no monthly review, which makes it the cheapest place for a cost to land and the most expensive place for it to accumulate.

The objections

The concept licenses unlimited retrospective argument. Every decision has unmeasured consequences, so any outcome can be explained after the fact by hidden costs that were supposedly there all along, and the explanation is unfalsifiable. It becomes useful only when the cost is named, assigned to a currency — hours, attention, risk, optionality — and given an order of magnitude, however rough. An unquantified hidden cost is a rhetorical move.

There is also a real risk of double-counting against opportunity cost. The displaced alternative and the hidden cost are frequently the same quantity described twice, and adding them produces a number that justifies whatever was already preferred.

What it rules out

It rules out treating the invoice as the cost. It rules out comparing options on recorded spend when they pay in different currencies — one in cash and one in weeks. And it rules out 'it isn't costing us anything' as a defence of anything that consumes attention.

It does not rule out accepting them. Most hidden costs are worth paying; what the concept requires is that they be named before the decision rather than discovered after it, at which point the choice is deliberate instead of accidental.

Sources

Bastiat, F. (1850). Ce qu'on voit et ce qu'on ne voit pas. · Coase, R. H. (1937). 'The Nature of the Firm.' Economica 4(16). · Ellram, L. (1995). 'Total Cost of Ownership.' International Journal of Physical Distribution & Logistics Management 25(8). · Frederick, S., Novemsky, N., Wang, J., Dhar, R. & Nowlis, S. (2009). 'Opportunity Cost Neglect.' Journal of Consumer Research 36(4). · Jensen, M. & Meckling, W. (1976). Journal of Financial Economics 3(4). · Williamson, O. (1985). The Economic Institutions of Capitalism. Free Press.