It would be easy to assume the arrival PIN gets sent to a customer's phone the same way everything else does — a WhatsApp message, a code to read and type back. That's not how it works, and the difference is worth explaining, because it's the part of the flow that actually proves someone is standing in the shop.
What the PIN actually is
When a customer taps "on my way" on their queue status page, that's a signal of intent — they say they're heading back. It isn't proof they've arrived. Proof comes from a second step: a 4-digit code printed on a card at the shop counter, which the customer enters once they're physically there.
Because that code exists only at the location, entering it correctly is only possible for someone standing in front of the card. A message sent to a phone can be read from anywhere. A code printed on paper at a specific counter can't.
Why this is the right trade-off
A queue's whole value depends on staff being able to trust what it tells them. If "arrival" could be confirmed from anywhere — a code texted to a phone, a button tapped from the car park down the street — the signal would mean less. Someone could confirm arrival, then take another ten minutes to actually walk in, and the shop would have no way to tell the difference between "here" and "on the way, again."
Tying the confirmation to something physically present at the shop removes that ambiguity. It costs the customer one extra glance at a card and four keystrokes. In exchange, staff get a signal that actually means what it says.
What this isn't
This isn't a workaround for a missing feature, and it isn't there to make the process harder than it needs to be. The "on my way" tap already handles the softer signal — letting a shop know someone intends to return, well before they've arrived. The counter PIN is specifically for the moment that matters most: confirming presence, not intent.
The two steps do different jobs. One tells the shop "expect me soon." The other tells the shop "I'm here." Collapsing them into a single message would make the flow feel simpler, but it would also make the second, more important claim just as easy to fake as the first — which defeats the reason the confirmation exists at all.