That may be the case for some, but for some others I've met in similar situations in developing countries, they were happy and felt proud to be supporting their families. I didn't feel like their primary motivation was fear. Not everyone is so complex or pessimistic.

I think the point is doing the job makes you feel valuable/appropriated by someone you care about (family in this case). Just like personal fulfillment, in that case, yourself.

No. It is the pride of independence. I can provide, rather than being a dependent.

It is literally being the one who has the power to make your family's life better, rather than being one of the powerless. Being able to provide your daughter with a better school, your mother with better health care, your family with a better place to live, feels to some the way "changing the world" feels to others.

I agree. The article puts "extrinsic factors (like the chance to earn a big bonus) or intrinsic factors (like personal fulfillment)" as the primary factors. The "third" motivation, and I'd say likely the most common, is "fear". Even if the fear is that your children will suffer the same servitude that you are experiencing.

Sometimes it is.

Sometimes it's the feeling that you can't make your family/race/school/tribe look bad by not working hard. e.g. "If I slack off on this job, they will think everybody who graduated from Stanford is a lazy unprofessional bum." or "My parents raised me to be a better worker than this."

Or, this "third motivation" is the desire to succeed so the family can thrive as a consequence of that success.

Sort of a half-full/half-empty kind of thing, really. I suspect the perspective you cleave to is a product of your personal outlook.