Corporations and business in general needs cheap labor as well as likes to drain other nations of valuable human resources (doctors, engineers, scientists and so on). If you are a big business it is beneficial to abolish tariffs, open the borders, so you can employ anyone from anywhere, outsource, move production to where labor is cheapest, transport materials and products, capture resources and so on.. or even finance & profit off both sides of a conflict/war. Essentially bourgeoisie mentality / values.
Politicians depend on people with money to back them during elections, these things go hand in hand, essentially oligarchies. Wealth means power to leverage and influence things in one's favor, which is why this has happened.
:> these people don't care how the nation, the culture or the local population is going to be affected if there will be conflict or not. In a way the very founders of the US were such wealthy oligarchs rebelling against the crown, because it was profitable. Myth tells of ideals, the reality however was land, money, power and slaves. Thats why most of them risked their lives, the big payoff at the end. (exceptions exist)
Merchants have no country and soon neither will the GDP producer slaves. The environment? See Planet of the Humans. The bottom line is what matters. Profit.