That would be my default interpretation too, but I've seen this phrase used plenty of times to mean "working hard", or "enduring work drudgery" (without any relation to ethical issues you mentioned), so I'm confused about the correct meaning of this term, and every time I see it, I have to infer from context what it is that a commenter is talking about.

The American meanings of work ethic relate to working hard or diligently. They don’t have anything to do with ethics. That would be under “work values” oddly enough.

Thanks for the clarification.