On occasions where I've showed up late at the gate and there is a zoo, I've gone up to the counter to check on standby or an upgrade, and if there wasn't an agent to talk to, I've stood there looking forlorn until someone makes eye contact and then showed them my boarding pass. On at least a couple of occasions, they've pointed me at the agent scanning boarding passes, who has then let me in ahead of the masses. This is an imperfect solution, of course.

If other people are standing in the Zone 1 line, I would have no hesitation asking them if they are zone 1, and going around them if they aren't. There is a reason the line is marked that way.