Similarly, child labour is still very common and as far as I'm told in some places even on the rise, so there must be more to the story of its disappearance from the west than "children make bad workers".
That is what made those societies successful anyway: freedom which brought innovation which brought prosperity. Not the fact that they were "western".
If that wasn't true, every employee would be at minimum wage, and Google wouldn't offer free lunches.
The evidence that free markets lift people up is enormous.
Today we have a large group of mistreated sweatshop labourers that produce clothes and gadgets for the industrialized world under conditions that would never be accepted in America, much less Europe. Are those conditions not a result of free markets? Companies who were free to move their production to places that were not encumbered with things like safety laws and minimum wages? And what in the world makes you think that those conditions will become universally a thing of the past without intervention?
No law in Cambodia forces seamstresses to work 16 hour days, no law is forcing the sweatshop owners to demand this of them, everyone involved is in principle free, indeed they are probably freer than I am in my country. That is why the works takes places there and not here.
The labour there creates billions of euros of surplus value that end up as profits for the multinational companies that employ them (directly or indirectly). There is enough money made in the clothing industry to pay decent wages to these people, just like there is enough money in many of the companies in Europe and America that employ the "working poor" to pay people what they need, but it is not done, because by and large companies pay people as little as they can get away with.
This is a problem that can only be solved empowering workers to make demands of their employers. Some workers are rare enough that they have this power by default - I know this, I am one of them, for now. But for the rest, the best way to empower workers is to allow them to band together, either directly in unions, or indirectly via progressive governments making sure that the legislative frameworks that companies operate under result in a decent quality of life, even for those in unskilled jobs.