I think in a vacuum this is mostly true. Yes, if we open markets to automobiles the price of automobiles for consumers will drop. I'm not so sure it holds in the case when you consider us opening the markets for automobiles, vacuum cleaners, industrial chemicals, semiconductors, etc...
At some point you eventually reach a state where we don't actually make things anymore and the entire economy is devoted to serving those who benefit from that trade. You end up with an economy based on food service, hospitality, retail, etc. As the owners of those trade arrangements diverge further and further economically from the overwhelming majority of the population it breeds a kind of resentful desperation. When we have a healthy economy where most people can support themselves with a reasonable salary in a self-respecting dignified way without licking the boots of the upper class society is healthier. It's hard to see how we do that with free trade.
At some point you eventually reach a state where we don't actually make things anymore and the entire economy is devoted to serving those who benefit from that trade. You end up with an economy based on food service, hospitality, retail, etc. As the owners of those trade arrangements diverge further and further economically from the overwhelming majority of the population it breeds a kind of resentful desperation. When we have a healthy economy where most people can support themselves with a reasonable salary in a self-respecting dignified way without licking the boots of the upper class society is healthier. It's hard to see how we do that with free trade.