Ok, got it. In that case, and with a possible exception of EU zone, there are no countries that allow doing what you described. For example, being a citizen of Canada I can travel almost everywhere w/o visas, but I cannot just fly to Italy or Mongolia or Japan and get settled to live and work. Nor would I be able to get a work-enabling visa easily. In other words the USA is not an exception, there is nothing unique about their free settlement restrictions.
The difference, is that US (and Canada I guess), unlike many other countries was founded on immigration and prides itself with that fact ("melting pot, yada yada.."). However it ended up as a country with one of the most complicated and difficult immigration systems in the world.
