edit : didn't mentioned that the interest i saw with the graph above was that it's usually considered cheaper to work in China, and that developing countries need to 'be competitive'/'lower their salaries' in order to attract investments. This graph points out to the existence of other factors than wages in order to 'be competitive'/'attract investments'. Perhaps that a country should( somehow) become wealthy enough to enable its own capitalists to invest in machinery, leading to 'higher salaries'/'more (productive )investments'/'higher competitiveness', i.d.k. Still don't know as well how China escaped the trap that every other country fell in.
China still has the competitive production costs because its labor productivity grew in lockstep with wage growth. So one operator making 10x as much product can be paid 5x as much wage and be cheaper per unit than an operator in a country where they make 1x product and are paid 1x wage.