i wonder why kyon the only servant who use white tux

I've been wondering about that too..maybe to make him stand out among other servants? Lol
But seriously, I'm curious. Hope the author will enlighten us. ( ︶▽︶)/

Just guessing but possibly it's to create contrast between the main couple. Like Kyon is allll white and pure and a precious baby, and Lucaon is dressed in all black and has the menacing aura of a master of jackasses. Basically I think the author just throws the white outfit there for appearances and it doesn't really have anything to do with the plot.