Not all, but many did for long time. Why?
So, are you saying we should have remained an agrarian society and protected those farmers jobs? Where would we be today had we done that?
With free trade there are winners and losers because of the unequal distribution of its benefits but, in the long run, the whole country is better off. Unskilled, low income workers are usually the hardest hit and governments cannot ignore the disruption and need to provide assistance to these people because they live in the short run.
I doubt the Mexican government is doing anything for their displaced people which is unfortunate but not surprising.
However, It seems misguided to me to avoid a policy that makes the whole nation richer because it makes some individuals poorer.