If you think a lawyer (using this occupation as a placeholder) in Mississippi and a lawyer in New York don't have largely similar standards of living when compared to lawyers in the rest of the world, then we are both using English but not using the same language.
You were talking about free trade in the post that I replied to. You seemed to imply that you find it acceptable, within the context of the EU, because the member-states have similar standards of living and labor laws. This is false. As I said, we do not even have similar standards of living and labor laws within the United States. Indeed, a lot of corporations go out of their way to locate their facilities within so-called "right to work" States, where wages are lower and the legal balance is tilted more in the employer's favor.
The same trend has been happening for years within the EU. Most of the Nokia phones I purchased over the years were made in Romania. Why? Wages are cheaper there than they are in Finland. Romania is the South Carolina of the EU and Nokia moved production there for the same reasons that Boeing built their new plant in South Carolina rather than Washington.
You're right to say that a lawyer in Mississippi will have a similar standard of living to a lawyer in New York. He may even have it better; he'll make less money than the New York lawyer, but the cost of living is significantly cheaper, so much so that he may effectively be richer than his New York counterpart. That doesn't change the fact that New York has it better when we look at average metrics, things like educational attainment, life expectancy, obesity rates, etc. And if we want to talk about labor laws and regulations, well, there's no contest between the Northeast and the Gulf Coast.