For a Civil Engineer to build a bridge that collapses, he has to be licensed and will be liable because there are standards to follow (strength of materials, calculus, etc). No such thing exists for software.
Could you be more specific then about what part of following DO-178C guidelines and FAA certification process you find inadequate, such that, "no such thing exists for software"?
I do not mean to belabor the point, but am genuinely curious what you might find to be an acceptable level of rigor for software. [EDIT: or perhaps you literally mean that no such level could possibly exist?]