There are other factors involved. There's really easy migration to Australia which has a stronger economy, it's common for people to have other passports so it's easier to move elsewhere because of that too, there's less of a belief that we're the greatest country in the world that could bias American emigration. America is also a big place, so people can move around within the country fairly easily if conditions for any particular group of workers in any particular place is bad, which isn't the case here.

It's not quite as simplistic as you make it seem.