would you feel better if they called it "zone red, zone blue, zone yellow"? What difference does it make?
Unseasoned travelers in Zone 1 (credit card holders) think they are boarding first. Zone 2 passengers think they are actually in the second group. After all, what should they expect given they are in Zones 1 and 2? They crowd the entrance, not realizing they are blocking access to the majority of passengers, who are boarding in one of the more-than-half zones that board before Zone 1. Calling those Zones 5 and 6 might have a Raid-like impact on gate lice.