The confirmation goes out by email at the moment of booking, with the address, the directions, the check-in window and the parking note. It lands in a promotions tab and is never opened.
Three weeks later the guest is driving and phones at nine at night from a village with a similar name. Somebody at the desk talks them in for fifteen minutes. Everything the guest needed had already been sent.
Email is not failing at delivery, it is failing at attention — and a property has no way to know which, because an unopened email looks exactly like a sent one.
The app a guest already has open is a different proposition. A confirmation on WhatsApp is read within minutes, comes from the property's own number so it is recognised, and can be replied to by a human rather than bouncing off a no-reply address.
The control that keeps it working is that the opt-in is per event. A booking confirmation and an arrival reminder belong there; a newsletter does not, and sending one is how a property gets its number blocked and loses the channel for the messages that mattered.
Why this matters to you: almost every "difficult arrival" is an information problem that was already solved and simply did not reach the guest. Moving the two or three operationally important messages to a channel people actually read removes a category of phone call rather than a single one.