As awesome as these algorithms are, I can never imagine use case.

Any time I need to turn something into uppercase or lowercase, it's user's input or something Unicode. Which can be in any random language, so all the crazy Unicode casing rules apply.

I mean, Czech could work by canonical Unicode decomposition and then re-composition afer case change ...but the input can be in Russian or Greek. I can't imagine accelerating that, or rather taking into account all the ranges.