This is an anomaly and left over from the time when middle class was growing after the 2nd world war. We (Western countries) are dismantling all the back stops and the process will reverse and move all the wealth to the few rich people in the capital class. When this process is complete the poverty levels in the west will equal those of the countries you mentioned, Afghanistan etc.

The USA and UK are leading the process since they started to pursue this goal aggressively during the 80s with Reaganism and Thatcherism.