Most planes crash because of something else than software... Most casualties in the medical domain are not caused by software... to say nothing about war casualties.

It's not sand in the oil, it's the lack of a filter, that cause a crash. It's not human error, it's badly designed UI. It's not aging, it's improper material choice. It's not a manufacturing problem, it's a design problem with the manufacturing process.

Software is just yet another imperfect engineering domain.

It's too easy to point to software engineering as fundamentally flawed without looking at all the flaws in engineering(TM)...

To round out your point: some failures are the result of perfectly valid cost/risk trade-offs.