A whole lot of software just supports a business, and a non-critical business at that. If my buggy software takes down, say, pets.com, well, first, the world won't end because pets.com is down for 8 hours, and second, pets.com wasn't going to succeed even if my software was perfect. That kind of software isn't like building a bridge; it's more like building a birdhouse. Nobody's going to die if it collapses. (OK, a bird might.)

Some software is critical. Safety critical, or running critical financial processes, handling medical info, and so on. That software does have technical standards.