In real world engineering, defects are part of the design and not bugs. Really they aren't even called defects, because they are inherent in the design.

Maybe you bump your car because you stopped an inch too far. Perhaps it's because the tires on your car were from a lower performing but still in spec batch. Those tires weren't defective or bugged, but instead the product of a system with statistical outputs (manufacturing variation) rather than software-like deterministic ones (binary yes/no output).

Which goes back to OP's initial point: SWE types aren't used to working in fully statistical output environments.

What is the utility of this sense of "bug"? If not all bugs can be fixed it seems better to toss the entire concept of a "bug" out the window as no longer useful for describing the behavior of software.

What is utility of any other sense? I expect null pointer to happen. It is still a bug. Even if it is in some kind of special situation we dont have time to fix.

> If not all bugs can be fixed it seems better to toss the entire concept of a "bug" out the window as no longer useful for describing the behavior of software.

Then those are bugs you cant fix. It is just lying to yourself to call them not a bug ... if they are bugs.