It made perfect sense that fugitives with clearly identifiable markings and well known faces didn't interact much with NPCs, but the 'long hallway' structure did get repetitive.
I could swear that the Chocobo theme tune had the words 'Huuman slaaaaves' in it.
Yet nobody at Nautilus gave Vanille and Sahz any trouble. These people have never seen a L'cie. There likely hasn't been one since the coccoon/pulse war, and that was what, 2000 years ago? I get that some of these people have long cooshy lives and die of old age at like 120 but there's still no living memory of what a L'cie really means. All the brands are well hidden too. You'd have to take off at least some article of clothing to see them, with only Hope and Snow being the ones to have brands are a part of the body normally exposed.
Think about that: Every L'cie is branded. Its very damned easy to identify them. Yet the people of Coccoon agree to a total purge when all you have to do is a body check. Find a tattoo, and boom, bullet to the head. Simple, and easy.
So, yeah, nobody on Coccoon knows anything about what a L'Cie really is, much less that they may be walking among them unless they're outed. They basically react because of whatever poorly explained dogma tells them to react that way. Its really kind of a frustrating plot hole.
So I don't really buy this "Need for cover" plot contrivance. If Palapolum hadn't already been a hot spot, I doubt that Lightning and Hope would ever have been known to the public at large. The rest continued to be unknown.