We hope that this cost can be lowered in the future.
The industry tends to lag behind academia by at least a couple decades. In the 90's, lots of research was being devoted to functional programming and the various applications of type systems. Now we see various companies starting to use languages like Haskell and ocaml. Nowadays, it seems like dependent types and program verification are popular in academia, so maybe we'll see some of that by 2030.
First of all, you need to correctly define the specification. Saying "the returned list is sorted" isn't enough because that would also accept lists that have nothing to do with the input, like [1,2,3,4,5]. Also saying that the list only contains elements from the input is also not enough because that would accept a returned list with duplicated or missing elements. To really make a specification that models what you want you need to say that the returned list is a sorted permutation of the input list.
Then, once you manage to get a formal specification that is actually what you want prout invariantving it is also hard. In the bubble sort case you need to figure you need to write down the proofs in detail, down to the point when you use the fact that comparison is a transitive relation.