It is commonly discussed that one way the empires of 16-18th would receive wealth from colonies is:
- Get raw materials from a colony
- Transport them to the empire
- Make more sophisticated products out of raw goods
- Transport the finished goods to colonies and sell them there.
For example here I read that
... the prevailing economic wisdom suggested that the empire's colonies could supply raw materials and resources to the mother country and subsequently be used as export markets for the finished products.
For me it is clear how you benefit from getting raw materials from colonies. But why would an empire transport finished goods back to colonies?
Why would an empire establish trade and exchange relations with a colony at all if it can just take all the resources for free (given that an empire is more advanced in technology and weapons)?
In other words, why would an empire need to bring back some finished goods to get something if it can just come to a colony and take everything?