Status Messages requires that important updates, form validation results, cart totals changing, search result counts, loading confirmations, be exposed to assistive technology through appropriate ARIA live regions or roles, so screen reader users hear them without their keyboard focus being forced away from what they were doing.
A common failure is a success banner that appears visually after a form submits but is never announced audibly, leaving a screen reader user unsure whether the action worked at all. This criterion is a frequent gap on single-page applications that update content dynamically.