It may be staffing but it is also a basic design issue. At the very least priority security folk could go down the same lane as the family people, although that would only put them ahead of three or four non-priority people. But really, is there a reason that there are only two very wide lanes running down that left hand side, the nexus one and the one that combines non-priority, priority, and family? Each lane is significantly wider than it needs to be and you could easily fit three lanes in, so that the priority people at least get all the way to the room with screenings, even if there is not a dedicated lane for them.

I'm keen to complain about this too but am not sure who to contact.