Actually experienced it...
I know this is against the rules of the Internet but I actually experienced this trial.
First off, they clearly hadn't got access to any other database, "Team" were mashing the "this passport matches this person" button on the manual gateway. My ePassport worked at all stages except this one.
The line of gates were just in front of the seating area pre-boarding, once through there was clearly no intention that you leave. There were no toilets. There were also not enough seats for everyone to sit down. You can imagine.
Random child tailgates perfect stranger as they scan through.
Another unrelated child backs away as parent walks through having lost concentration because of extra gateway.
Original random child miraculously teleports back outside the barrier without warning, or parents who have now gotten into the area.
"Team" goes into meltdown, hilarity ensues.
Did not remove either my beard or my wrap -around Oakleys whilst "Team" manually confirmed I matched my passport and stored photo?
Can't see this working myself, can see people getting very, very annoyed.