Why Huge Labor Productivity Gap?

According to the Statistics on labor productivity¹, there is a massive gap in labor productivity between different countries. As you can see, for example, for the group of countries on the top of the list, Luxembourg, Ireland, Singapore, and the United States respectively have $128.1, $122.2, $73.7, and $70.6 labor productivity per hour. For the group of countries at the bottom of the list, the labor productivity is very different. For instance, this number for Eritrea and Somalia is only $2, and for some countries, it is less than a dollar.

Also according to the Unemployment Rate² statistics, in some countries, the unemployment rate is very low but in some countries like South Africa and Nigeria, the unemployment rate is more than 30% of the labor force.

Based on the things that we learned in week # 4 about labor markets and income, please explain that what is the main reason for the huge gap in labor productivity and also unemployment rate between the countries, and what is the solution for the poor countries to increase the labor productivity and decrease unemployment rates for their economies.

Please search about it on the internet and use at least three sources.