It's precisely because they can't care that they are by definition bullshit machines. See https://link.springer.com/article/10.1007/s10676-024-09775-5

I disagree with the article’s thesis completely. Humans are the ones that spread the bullshit, the LLM just outputs text. Humans are the necessary component to turn that text from “output” into “bullshit.” The machine can’t do it alone.