The coating depends on the jeans. It's often a polyurethane or resin coating. Over time, this is the stuff that wears off. Then, after an even longer time, you should get fades (I think most of them do this).
TFDBC are weird, though, from what I've read. The coating doesn't wear in the same way as other coated denim. The high abrasion areas actually get shinier with wear. After being machine washed, they start to lose their coating, though, as expected.