In the $7.95 transaction, the buyer spent a higher percentage of their wealth buying the sweater than the $80 transaction today. By keeping the inflation adjusted price the same but boosting a buyer's disposable income, free trade has allowed the buyer to spend more of their income on other things within the domestic economy.

Multiply this scenario across every buyer (i.e. everyone) in the domestic economy, the increased productivity has allowed for more consumption and economic growth.

Let's consider the scenario in reverse, if keeping $7.95 locally is the best policy, would you advocate someone in California to not buy goods made in Missouri? After all, labor is much cheaper in Missouri. How about someone in San Francisco not buying goods from someone in Central Valley?

An average person could build a house themselves and keep the money they would spend in their "domestic" wallet economy instead of paying some contractor. Why do we hire contractors who might live in a far away town then? It's because it's mutually beneficial. I get a house that's better constructed faster than I could ever build it, the contractor gets compensated for their money. The time and productivity I saved in that transaction far outweighs the cost paid to the contractor.

And why is that? Because it made sense based on the options provided to them. And who decides what those are? The people with money and power, not the consumer.