One holiday. Two systems that needed to know who we were.

The first made me tell it three times. The second asked once, at the door, and then never again.

Heathrow

There were three of us on one ticket at the British Airways self check-in kiosk. One booking. One destination. Three passports, three bags.

The machine made me prove that three times.

Scan a passport, print a boarding pass, tag a bag. Scan the next, print, tag. Again for the third. Tedious, but fine - I've done worse. Then my son's boarding pass flagged, because his passport needed a visa check, and we were sent to a staff desk. There, a person verified not just his visa but all three of ours, one at a time, while a queue built up behind us.

What bothered me wasn't the wait. It was that the system already knew we were one party. One ticket, one destination, three linked passengers - that relationship was sitting right there in the booking, which is exactly how most airlines check three bags under one reference without asking three times. But the interface wouldn't use it. It made me re-assert, by hand, something the database already held.

And the visa check could have happened in the same breath as everything else. Verified at the kiosk during step one, or handled at a single manned counter in one pass. Either would have worked. Instead the friction got smeared across a machine, a walk, and a queue - and the family with the child was the one made to absorb it.

Billund

A few days later we were at LEGO House, and the contrast is almost unfair.

I'd booked online. A QR code arrived by email. On the day, I scanned that one code at a machine and collected three wristbands - each printed with a name, each carrying its own code. That was the last time the building asked who we were.

Everything after that was a wrist swipe. Enter, exit, build something, photograph it, swipe. It attached itself to whoever built it. My son didn't need me to hold his photos or remember an account - his band was his, so he captured his own builds and collected his own videos without routing anything through a parent. At the end of the day I entered the memory pin I'd been given hours earlier, and everything we'd made was waiting.

None of that is technically remarkable. A QR code, a wristband, a lookup. What's remarkable is the restraint: the identity was issued once and then honoured everywhere, and the collecting happened without anyone having to manage it.

British Airways had the same information. It just made me carry it.

The three questions

Put the same three questions to each and the difference stops being a mood and starts being a design.

How many times did it ask who we were? Three, then once more at the desk. Versus once, at the door.

Who carried the context between steps? Me, in my hands and my head. Versus the band.

What happened at the exception? Bolted on as a separate queue. Versus designed in - or rather, designed out, because there was nothing left to except.

The interaction design language for this is decomposition. Break a complex task into steps a person can complete without thinking. Both systems did that part well; the kiosk flow is perfectly legible. But decomposing is only half the job. The better half is recomposing - collapsing those steps back down wherever the system already holds the context to do it for you. Heathrow decomposed and stopped. Billund recomposed all the way to a wristband.

The other word worth having is seam. Friction doesn't sit inside steps; it gathers at the handoffs between them, and especially at the handoff between a machine and a human. Kiosk, walk, desk, walk back. Every seam is a queue.

The obvious objection

LEGO House is a closed venue with one operator, no regulator, and no legal exposure if someone's paperwork is wrong. British Airways is stitching a border check into a commercial flow, and a visa is a genuine exception with a genuine reason for a human to look at it.

That's fair, and it explains why the step exists. It doesn't explain why it happened three times. It doesn't explain why it happened after the kiosk rather than during it. The exception is real. The fragmentation around it is a choice.

Why I keep thinking about it

Because a check-in kiosk is a checkout flow with a captive user.

Every one of those seams - every point where the interface re-asks for something it already has, every handoff between two halves of a process that should have been one - is a drop-off point. In a funnel you'd see it in the numbers: people leave. At an airport nobody leaves. They can't. So the same design flaw doesn't show up as an abandoned cart, it shows up as a family standing at a desk with a queue behind them, and nobody logs it anywhere.

The airport is just more honest about the cost.

Same trip. Same child. In one system he was the reason for the extra step. In the other he was a user with his own wristband.