Comment by QuadrupleA

I don't think formal verification really addresses most day-to-day programming problems:

    * A user interface is confusing, or the English around it is unclear
    * An API you rely on changes, is deprecated, etc.
    * Users use something in unexpected ways
    * Updates forced by vendors or open source projects cause things to break
    * The customer isn't clear what they want
    * Complex behavior between interconnected systems, out of the purview of the formal language (OS + database + network + developer + VM + browser + user + web server)

For some mathematically pure task, sure, it's great. Or a low-level library like a regular expression parser or a compression codec. But I don't think that represents a lot of what most of us are tasked with, and those low-level "mathematically pure" libraries are generally pretty well handled by now.