Bidets don’t use soap? Well, I use soap on every use, what kind of bidet instructions do you follow up? Sponge and hands, a bidet is like a mini shower in your groins without a full body implication, is just a washbasin at a convenient height… don’t you wash your hands and your face in the morning with soap in the washbasin?
EDIT: Probably we imply different things for “bidet”, I got South European one in mind…