ah ... economics
Here's how it was explained to me (it was late, the pub was about to close, so the economist doing the explaining had to use some heroic simplificatins, but still ..)
Basically, it's about the consumers. If everyone in the state has a good job, they can afford to buy stuff. If company A moves its operations offshore, but continues to sell stuff within the state it makes a profit, because its goods are cheaper. However, the pool of available consumers has shrunk by the number of jobs moved offshore.
Currently the US is in a position where the consumer pool is shrinking as more and more companies move jobs offshore and try to sell to the diminishing number of people who have good jobs within the state. (Not a lot of people are buying stuff in the rust belt right now) Everyone knows that the way to stop this impoverishment of the nation is to stop offshoring. But any individual company that tries this will be broken by the competition. It has to be the government.
It's rather like raising the minimum wage - when this happens there's more money going around (poor people spend money, the rich bank it). However, no single business can unilaterally raise wages and stay competitive.
Some economic actions have to be done by the gubmint for the common good.Sort of government by the people for the people ...?