I didn't see mot of those episodes, but from perusing Memory Alpha, I didn't see anything about White besides it was used to keep the Jem-Hadar soldiers working. Did it have a drug-like effect in non-Jem-Hadar? Or has White just ascended into pure meme status?
I think it's so you get centered as much as possible so you can reach the conveyor on the first try. When cars were more standardized in width. And so they don't waste space.