I agree that it's kind of hard to claim criminal negligence for software bugs, after all it's very hard to make something bug free and software is that weird edge case where you can tell someone exactly what it does, but not in a way that is useful for preventing problems.

That said in extreme cases like e.g. airplanes I think it would be fair to consider it negligent when code is just brought into production without any kind of debugging or testing.

I guess the stakes decide when something is or isn't negligent.