Barriers to trade were barriers between nations and, hence, caused wars. As the barriers came down, global trade surged. The results have been distinctly lopsided. Most Americans are hardly better off now than they were 30 years ago. The rich, however, have done extremely well.
Companies switch their operations overseas to take advantage of cheap labor.
At home employees are thrown out of work and may have to take a cut in pay. On the other hand, profit margins along with the value of the company stock soar. Hence, the growing income disparities in America. The figures are remarkable. Since 1977 the incomes of the top one percent of the population have risen dramatically.