[TJSomething]

Under this idea, most engineering isn't engineering. Some of the oldest engineering is ad hoc battlefield engineering to construct siege engines and building tunnels to deliver explosives. That frequently only needed to work one time.

With bridges, you only need that high confidence because there are high costs and risks. Also, the stakeholders are usually governments, who require very predictable results. All that effort is worth it because the artifact will be useful for a long time for a lot of people.

It might be okay if some widget only lasts for 6 months. So, you empirically shave off material until it's as cheap as possible while failing at an acceptable rate.

The cost of shipping is low for software, so the risk profile is even more different. This can be shifted for high stakes software and I think there are some social issues there, but many things are shaped more like Facebook than aircraft control systems. They can fall over and no one's going to actually die.

I think the core of engineering is in evaluating these tradeoffs and figuring out where you can expend effort most efficiently.