Accessibility work is often scoped as a compliance checkbox, which undersells what it actually does to a product. Clear focus states help every keyboard user, not just screen-reader users. Sufficient color contrast helps everyone reading in bright sunlight. Sensible heading structure helps anyone skimming a long page.
Treating accessibility as a parallel afterthought, bolted on near launch, is both more expensive and less effective than designing with it from the first wireframe.
The teams that do this well don't treat it as a separate task at all — it's just part of what 'done' means for any component.
