For most of the cases where formally verifying _code_ is important, "unit tests" aren't enough. If the person who writes the proofs leaves, you hire someone els

For most of the cases where formally verifying _code_ is important, "unit tests" aren't enough. If the person who writes the proofs leaves, you hire someone else to write proofs. Otherwise you don't have a business model. For most of the cases where formally verifying _designs_ is important (most of the industry), formal specification languages are 1) not actually that hard to learn, and 2) exist distinct from the code, so you can throw them all out if you really need to and go back to flying blind.