Accessibility is achieved either by designing for varied users from the outset or by adjusting a completed design on request. The two routes lead to noticeably different results.
The point at which decisions are made
Inclusive design treats the range of human capability as a design input alongside cost and performance. Constraints are known before the structure of the product is fixed.
Accommodation begins after the design is settled and a user encounters a barrier. The available responses are limited by choices already embedded in the product.
That sequencing explains most of the cost difference. Changing an early decision is cheap; working around a fixed one usually means adding a parallel mechanism.
Coverage differs in kind
An accommodation addresses one person's barrier. Anyone with a similar difficulty who does not ask, or does not know to ask, encounters the same obstacle unchanged.
An inclusive design change applies to everyone using the product, including people who would never request an adjustment and those whose needs are temporary or situational.
Captions, adjustable text size and step-free entrances are the familiar examples, each originally developed for a specific group and now used far more broadly.
Disclosure is a cost users bear
Requesting an adjustment usually means explaining a personal circumstance to an employer, institution or service, often more than once and to people with no obligation of confidentiality.
Some people decline to ask for that reason and manage the barrier privately, so recorded accommodation requests understate the number of people affected.
Designs that remove the need to ask also remove that calculation, which is a substantive difference in experience rather than merely an administrative simplification.
Neither approach replaces the other
Inclusive design reduces the number of adjustments needed but cannot anticipate every situation, since needs vary in ways no general design can cover.
Individual accommodation remains necessary for circumstances that are genuinely specific, and legal duties in many places are framed around exactly that individual obligation.
The practical position is a design that handles the common range well and an accommodation process that handles what remains without excessive proof.
Procurement decides which route is taken
Most organisations buy systems rather than build them, so accessibility is determined by supplier choices made long before purchase.
Requiring evidence of accessibility in tender documents shifts the decision upstream, where inclusive design is still possible, rather than leaving it to later adaptation.
Legal duties framing these obligations differ by country and sector, and the balance they strike between anticipatory duties and individual adjustment changes over time.