Because many American Conservatives believe that NAFTA has leeched our labour force and fed "American Jobs" to the Mexican economy. Many NAFTA skeptics cite the loss of U.S. manufacturing jobs as a reason to criticize NAFTA and to be wary of future trade deals. According to the CFR, the U.S. auto sector lost roughly 350,000 jobs between 1994 and 2016. Many of those jobs were taken up by workers in Mexico, where the auto sector added over 400,000 jobs in the same period.
Besides that (the main and largest reason), the only other reasons are that NAFTA hurt the economic prospects of Mexican small farmers and small business owners, and that NAFTA suppressed wages for non-college-educated workers in the U.S.
Geologists have used two main types of evidence to learn about Earth's interior: direct evidence from rock samples and indirect evidence from seismic waves.
