The four types of people in the world are:
1. Those who use bidets.
2. Those who wish they could use bidets but don't because they don't have access to them.
3. Those who don't really know about bidets, and therefore aren't particularly bothered that they don't get to use them.
4. those who know about bidets and might or might not have access to them, but through an act of willful stubbornness continue to assert that they actually prefer to put their hand down there to wipe excrement from their [ahem, ahems] with bits of dry paper.
This is, perhaps, the key moral issue of our time. And although I am hesitant to pass any kind of moral judgment on anyone else, ever, I have to say that the final group really gets my goat. These are the sort of people who are so invested in the idea that "the way they've always done it" is the right one, that they will actually turn off their brains and argue against the obvious in order to avoid having their paradigm shifted in a less feceous direction.
Feel free to extrapolate this principle out to whatever other sort of willfully ignorant behavior you've ever encountered.