Usually, when a group of people start screaming and crying about wanting "free trade," they actually mean that they want just the opposite of true free trade.
US employers routinely complain that they should be about to the hire the best bargains they can find, no matter where in the world those workers live. That would be "free trade," those employers constantly tell us.
The employer's assertions seems plausible enough, until you stop and remember that H1Bs are hired on very different terms than US employees. Unlike a US worker, when an H1B has gained experience, that H1B can not demand a raise, or threaten to leave. It is very difficult for an H1B to change jobs. The H1B can not freely market his/her skills. Frankly, that H1B is denied "free trade" when it comes to finding another job. And that denial of free trade, is exactly what US corporations want.