A guest mentions a severe shellfish allergy while checking in. The receptionist writes it on a sticky note and means to tell the restaurant. The shift changes at four. The note is under a keyboard.
At eight the same guest orders from the à la carte menu and the kitchen, who have never heard any of this, plate a dish finished with a fish sauce.
Everyone involved was competent and nobody was careless. The information simply had no home: it was told to a person rather than recorded against a guest, so it survived exactly as long as that person's shift.
When the allergy lives on the guest profile, the warning appears at the register the moment their order is keyed — with the coded allergen and the free-text qualifier together, because "mild intolerance, avoid cross-contamination" carries information no tick-box can. An ungraded severity is treated as severe, never mild, because an ungraded note means nobody asked rather than that the reaction is minor.
Why this matters to you: this is the one operational failure in hospitality that can seriously hurt somebody, and it is caused by a note rather than by a decision. It is also the one your insurer and your local authority will ask about. A record that follows the guest from the desk to the pass is not a feature; it is the difference between a policy you describe and a policy that operates.