Birthright citizenship in the U.S. is hardly about a desire to "extend rights and privileges to outsiders". The 1866 law was voted during the Reconstruction after the Civil War, to guarantee civil rights for Blacks [1]. It was later introduced in the Constitution to make it more robust against repeal [2]. Republicans have talked of repealing the amendment precisely because it is used (abused) by "outsiders" [3]. I'd like to see better examples to support the assertion that the U.S. has been more liberal towards outsiders than nearly any other developed country.
Regardless of the initial motivations for the 14th amendment, it was interpreted very early as extending a broad birthright citizenship: http://en.wikipedia.org/wiki/United_States_v._Wong_Kim_Ark. And the fact is that the US has abided by it and extended citizenship to people born on U.S. soil in a way France or Germany or any of the other countries who get snooty about U.S. foreign policy never have. Those countries are quite content to have large number of people born on their soil that can't claim the privileges of citizenship (though their attitude is better now than it was in the 1970's or 1980's).
My brother was born just a few months after we immigrated to the U.S., and he was a U.S. citizen right off the bat, as much a citizen as anyone else and eligible to run for President. That wouldn't have been true in any Western European country.
To me, that suggests a pretty liberal attitude towards outsiders, i.e. making it tremendously easier to transition from being an "outsider" to no longer being an outsider.
To me the origin of birthright citizenship in the U.S. as a means of guaranteeing civil rights to Black people is more significant than having the Supreme Court interpret the text of the amendment in the rather obvious way. On the other hand, it's true that senators acknowledged the consequence the law would have on children of foreigners [1], so that speaks for extending rights to outsiders. In any case, I'd like to see other examples supporting (or contradicting) the view that the U.S. is particularly nice to outsiders. It's rather average on the issue of citizenship through marriage I think. It's obviously not very nice on issues of privacy (NSA scandal) as well as some basic human rights (Guantanamo).
[1] http://en.wikipedia.org/wiki/Civil_Rights_Act_of_1866
[2] http://en.wikipedia.org/wiki/Fourteenth_Amendment_to_the_Uni...
[3] http://www.washingtonpost.com/wp-dyn/content/article/2010/08...