I don’t think even your proposed solution would yield the results you’re seeking. Even if the software were provably correct and never updated, it has to operate on hardware. Hardware will fail. Battery life will degrade, screens will crack, power cables will fray. Even other (real) engineering disciplines don’t guarantee 0% failure, they guarantee tolerances.

Metal forks don’t lose a prong, but their prongs do bend. They do get scraped in garbage disposals. They do get hot when left too long on a heated surface. Some (silver) forks are considerably softer, amplifying those failure modes. And while I’m sure there must be fork vendors who offer solutions with guarantees against those failure modes—there are niche products for nearly every imaginable niche—the vast majority of people knowingly buy forks with these known limitations, trading some reliability for economy and utility. If everyone had the expectations you seem to have, very few people could afford forks at all, and they very well may not have been developed because the market would be so small.