Do Uighurs value hard work? Tibetans? Subsistence farmers? City-dwellers? I don't really know what people mean when they say that the Chinese "value hard work". Which Chinese?
See how these questions add nothing to the conversation?
If the conversation is about China collectively, then it's not invalid to make other statements about China collectively. If you disagree with the parent's assertions about China, then let's hear it, but just pointing out that China is really big does not tell us anything we don't already know.
I'm saying I have no idea what a statement like "the Chinese value hard work" means. It is not testable or quantifiable, and it's genuinely meaningless. Now maybe you could publish some survey data that shows Chinese people more value hard work. That might add something to the conversation.
People don't treat populations and individuals as the same thing; the population is its own entity with its unique properties, and, obviously differences. The question is whether those differences are sufficiently exploitable. This is how policy works. If you are saying that you can't generalize over a population, you're saying that there are roughly zero between-population differences that are exploitable for strategic policy. Random things are unstrategizable.
I think that the Chinese and Japanese value hard work more than Americans and Canadians, and I think so because Americans and Canadians have an unfortunately true belief that intelligence is highly predictive of performance, and also that intelligence is not meaningfully improvable. On the other hand, I think that Chinese and Japanese people have the belief that effort is a far better explanation to performance.
The problem is that performance must surely be at least a combination of effort and ability; a depressed person may have the bodily ability to pick up the phone for their friends, but they might not care anymore.
I thus say this: if you go looking for studies on cross-cultural pedagogy, I claim that you're going to find that American and Canadian students are significantly more likely than Chinese and Japanese students to avoid harder challenges, to pursue easier challenges, to practice mastered over unmastered material, and to avoid a problem after poor marks. Does this speak to all work? Of course not. But it's a window into culture, rather than just comparing mean hours studied or worked between populations.