What is the relationship between a country’s employment structure and its level of development? why is this the case?

The employment structure of a country depicts the majority demographics of the labor force in the country and the major labor sector of the country (primary, secondary or tertiary). The developing countries’ economy will have the majority of its labor force mainly in the primary labor sector (raw mineral extraction) while  most developed country's labour force is mainly in the tertiary (service industry) sector.

The primary labor sector involves the use of more human labor and less use of machinery. This, therefore, raises the costs of production (and the costs of the goods) and little value-addition to the products. The profit margins are low.  In tertiary labor sector, automation reduces costs of production and profit margins can be high without raising the costs of goods exorbitantly.