[superswordfish]

Not all software requires the same degree of rigor in design and implementation. Software has bugs, but it sounds like you'd prefer if such software were never written in the first place. Regarding risk, it's as likely that the super-educated "engineer" drops unfiltered input directly into a SQL query as it is that Joe Programmer has the chance to corrupt data with a concurrency bug.

[badminton1]

Bugs and defects will happen at the time of implementing functional and non-functional requirements no matter how strong your preparation and problem solving skills are. But they differ since assumptions would differ in nature.

Many people would work on a problem until it works (or stops being an obstacle). But it takes some preparation to understand if an implementation is acceptable from a non-functional requirement standpoint.