The erosion of the American middle class is of little concern for one simple reason: it no longer matters much on the global stage. All that Global Corporate America needs from America is a stable foundation that won't offer up any surprises or spots of bother.
The concern for domestic jobs is mere political expediency. U.S. corporations are pulling $500 billion in profits from non-U.S. sales, and they hold $1 trillion in stashed overseas profits in various tax havens. All the growth in their revenues and profits are coming from non-U.S. sources. Spending $3-$5 billion on lobbying and campaign contributions is an "investment" with extremely high returns: for that small sum, U.S.-based global corporations make sure the U.S. government and citizenry don't become overly burdensome or obstructive.