Final answer:
Trade benefits societies by allowing countries to specialize based on comparative advantage, even if one country has an absolute advantage in all goods. Specializing in goods where a country has the lowest opportunity cost allows for a mutually beneficial exchange between nations, leading to maximized efficiency and gains from trade.
Step-by-step explanation:
Society gains advantages through trade mainly due to the ability to specialize resources in areas where the opportunity cost is minimized. In cases where one country has an absolute advantage in all goods, it might seem that trade would not be beneficial. However, the concept of comparative advantage explains why there are still gains from trade. Even when a country is more efficient in producing every good, it still benefits by specializing in goods for which it has the lowest opportunity cost, meaning it sacrifices less in terms of other goods foregone. Therefore, both countries can benefit from trade by focusing on their respective comparative advantages.
For example, if a high-income country is highly productive across the board but has a slightly lower productivity in producing wine compared to computers, it should specialize in computers and trade for wine. A low-income country, even if less efficient overall, might have a lower opportunity cost in producing wine, and so it will find it advantageous to specialize and trade for computers. This specialization and resultant trade allow both countries to enjoy a diversity of goods at lower costs than if they tried to produce everything themselves.