Arguably, the existence of nuclear reactors which don't fail safe under any contemplated crisis is a hardware bug. It's possible to design a reactor that can be ruptured by a bomb or earthquake, which will then dump core into a prepared area and cool down.

This kind of physics-based safety is obviously not possible for airplanes.

I should have said “commercial airplanes are among the most important and critical things that use software.” It’s obviously difficult to determine the objective most important use case.