Firstly, I don't think most jackpots are actually designed to be provably fair(you are free to tell me about one site that has provably fair jackpot, in dice to prove me wrong).
I don't know of any provably fair casino that doesn't have a provably fair jackpot. Coinichiwa.com for instance has a jackpot that is almost the same as dadice, but they've made it provably fair (which is just as easy as making it not provably fair) they just use values that are verifyable.