[SentientNo4]

Computer software does not exist in isolation; it is built upon layers and layers of abstractions, starting from hardware and ending with your framework/language of choice, resulting in a system so complex that no person alive is able to grok it in it's entirety. Bugs can be found in any of these hundreds of separate but interoperating layers, and no entity it's going to assume full liability for this entire construct.

A better analogy would be if the bridge was interconnected with every other piece of infrastructure in it's environment, from the buildings in vicinity to the ground it's built on, and all of these were in continuous shift and transformation. No sane engineer would take full responsibility for designing and building such a bridge.

And I haven't even touched on the subject of money and it's implications. "Whereas physics is math with the constraint of reality, software engineering is math with the constraint of money."