They made a few bluncers here. Due to FRA's layout and reputation, people end up going through security and to the gate seating area way before the ground handling staff have arrived, and as you see the seating reflects around the gate to airbridge/bus route. No easy solutions to this since the gate are also the check-in staff, so until 1 hour to departure they have to be on the check-in desk, then it's not much faster for them to get through security than passengers. Consequently they will be at the gate perhaps 30 minutes to departure, and fairly close to boarding, by which stage the gate is filled with passengers. So they ask everyone to leave the gate area, and then scan the boarding pass as they re-enter, and yes they are supposed to glance at the passport at that stage. Now boarding on to the airbridge is allowed at this point, and yes there can be a 5 - 10 minute gap where you are standing on the airbridge waiting for the cabin crew. That is undesirable, from my perspective, and I don't participate in it, but is SOP at a lot of locations, including LHR potentially, and not FRA related. I think the SOP says the waiting time should be short, so if the cabin crew really aren't ready they should hold people back from the airbridge. The problem then is a lack of space which makes it trickier for the gate agent to close up the flight.