This won't work, because individuals have different incentives than the airline. The individual wants to board early so that there is plenty of space for his/h

This won't work, because individuals have different incentives than the airline. The individual wants to board early so that there is plenty of space for his/her bag in the overhead bins, and also wants to board at the same time as family/friends. It's only the airline that wants the "efficient" boarding. Now add this to the fact that zones are almost never enforced: regardless of what's on my boarding pass, I usually just go when they call "Zone 1" or Zone 2". They've always just let me through without a comment.