So, while it's 12 hours at the office, it's not 12 hours working at your desk. It's probably more like 8-9 hours by American standards where you have a quick lunch, don't take an afternoon siesta etc.
The mythology of the ultra-hard-working Chinese is just that. Americans work pretty damn hard too but the optics are different. Americans also consider the hours at work as wasted time, with people who are irrelevant to their "real" life (the L in WLB), whereas the Chinese consider the socialization and the relationships of work to be pretty core to their life experience.
Also, the Chinese don't raise their own kids. The grandparents raise the kids while the parents focus on earning money for the family. The parents in turn are expected to raise their grandkids. Some kids don't even live with their parents until they get a bit older (around 10-12).
The West is still mostly oblivious to the Chinese way of life.