Explain why the produce from tropical plantations are profitable to the local communities that grow them but not as profitable as finished goods

Tropical plantations provide a good source of income for locals in many countries because they produce crops, such as cocoa, rubber and tea, which are used throughout the world.  But the produce from them are usually raw materials that can be used in a more profitable product.  Although the communities do benefit there is more profit in the finished products.

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