They don't bleach it, they refine it, don't you listen to them? And maybe the lack of durability has less to do with the type of carnauba, than with the amount, or the salad oil or suntan lotion or whatever else is in there.
"Bleaching" is a popular belief of producing a "white" wax, but it will change the molecular composition of the wax. There are several ways to refine a carnauba extract into white, in which one of the ways that's generally accepted is a form of bleaching the wax. Let me find this link.
