The idea of opportunity costs are found in the midst of this video. Many of the cars that are produced in countries overseas would be in very high demand in the US. They are reliable and cheap, but the problem is that they would be considered illegal by US law because of their safety shortcomings. Overseas car manufacturers would need to put in several new safety features to accustom themselves to US law and then pay the extra tariffs to get them there. Instead of having a cheap car, it now increases dramatically in price. The opportunity cost here, or the next best option, is instead of purchasing the cheaper car (the overseas ones) the extra criteria has forced Americans into buying cars here.
I agree, if cars from other countries were not sanctioned by the US government, they would be a very good option for many lower and middle class citizens.