I think that is mostly an ARR thing over all. There is almost no diversity in how npcs look even by the time the Domans come into the story. For instance a lot of the earlier depictions of Ala Mhigans are Hylander Hyurs wearing the Hempen Camise/Undershirt depending on the npc's gender. That being one of the times they use that top to mean oh this person is a refugee and thus poor. Look at them they're only wearing bits of leather held together via cords. Or they are a miner or some kind of day laborer. Not that I understand why they chose to show this person who works in the hot sun all day or in a mine should be wearing something that shows off so much skin. Heck even combatants that fight in the blood sands tend to wear those tops and I'm just going but why? I wouldn't want to end up taking a dive and having the sand in the arena scaping layers of skin off.