But the first person or team who realized that you could put a computer in an aircraft weren't solving a known problem - however they were using engineering methods, which is why it's very rare for avionics to (literally!) crash.

Here's my theory: we do know how to build very high quality software in a repeatable way. However very few organizations are willing to pay what it costs to do that, and that is why most software is so bad. Admittedly a lot of people writing code these days are "cowboys" (they don't care and neither do their clients, they just want speed) but that doesn't mean that the body of knowledge doesn't exist.