Why does economic growth in a country usually lead to less employed in manufacturing but more employed in the service industry?
As the country develops and the economy grows, peoples wages go up. Manufacturing industries compete globally, they have to keep cost of production low. Automated manufacturing typically stays in developed countries where the labor of highly specialized engineers is typically more readily available, however; when the manufacturing requires unskilled human labor, this tends to be exported to poorer countries whose people can do the job for less. Which poor country gets these jobs is a whole different ball game, but these unskilled jobs tend to be too expensive when done by a peoples who's country require $15 minimum wage.
Automation is the answer!
That could happen only in the highly developed economy, such as the US which has the share of service sector more than 70%