They might even care, they just don't know any better. When the typical scientist "learns to code", there's no one around telling them how to do proper software engineering.
At best, they engage in the polite fiction that it just doesn't matter, because all that code is inherently "throwaway" stuff that's only used for playing with in the context of research. Of course even that is wrong, the code doesn't really disappear like that.
No. Scientists are smart people. It's not that they don't care or don't know better, it's that they have different priorities. Every scientist I know is smart enough to be well aware that they don't have the know how for proper software engineering, but they also do not have the time or resources to learn to write code the way you would for a long term product.
I would not be patronizing to these people, they are very smart. They just live and work in a world that is completely different from technical product firms in pretty much every regard.
You're just rephrasing the "throwaway code" polite fiction. Increasingly, publishable-quality research is expected to be publically reproducible, and that means the code must stay around, potentially in the "long term". Every scientist loves it when their research gets cited a lot, right? Well, those citations become worthless if you can't reproduce the research because the code is an unsurveyable mess relying on bitrotted, unsupported external components.
At best, they engage in the polite fiction that it just doesn't matter, because all that code is inherently "throwaway" stuff that's only used for playing with in the context of research. Of course even that is wrong, the code doesn't really disappear like that.