So it's not just cheaper, it's also more expensive.
The operative fact (in the U.S.) is that a company such as Toyota can produce a car with fewer man-hours (unionized or not) than its U.S. counterpart. There is your advantage . . . the exchange rate for the currency is just a smokescreen.
The unions outlived their purpose decades ago. You seem very intelligent and I’m not sure how to react when you dismiss the exchange rate.