First, NAFTA was not about free trade. It was about reducing barriers that made U.S. companies reluctant to invest in Mexico. It did nothing to help American companies stay in America nor did it make investing in America more attractive. Remember “that giant sucking sound”. Make NAFTA a two way street.
Second, Mexico had to agree with a U.S. type patent system for prescription drugs which led to considerably higher drug prices when drugs were made in Mexico but they were still cheaper to make in Mexico.
America lost from NAFTA. The market was highly regulated which is anti-American. It lowered the cost to produce cars, textiles and farm products in Mexico which made American car manufacturing higher by comparison. Auto makers paid the price with jobs lost to Mexico. Same for drugs and farm products. America’s loss was Mexico’s gain.
NAFTA is part of the reason President Trump will build a wall and Mexico will be happy to pay for it. Economists are against Trump cancelling NAFTA but with their lousy records of poor economic forecasting no one need pay them any mind. .