It's also not aviation or medical. So perhaps it's more common than you imagine.
Before suggesting to use LLMs to completely rewrite this sort of software, there is a reason why compilers need to be certified to operate in safety critical environments. Not everything needs to use LLMs as the solution to a problem.
I would go as far to say that using an LLM in this context is the wrong solution and is irrelevant to critical systems. Maybe some here see everything as tokens and must solve everything in the form of using LLMs.
Rewriting a toy web app using LLMs from Javascript to Typescript is great, but isn't good for safety critical systems.