"Two years ago, the European Union admitted 10 new members. Like Mexico, all of these nations were poor, some of them fairly backward and most recently ravaged by war and dictatorship."
The difference is that 10 new members are poor mostly because of historical events like WW2 and next almost a half century of communism. Anyway Slovenia and Czech Republic have already GDP per capita higher than Portugal and almost as high as Greece. Hungary is not far behind and the rest need a decade at worst to join "the first world" club. Maybe I am wrong, but in case of Mexico the problem seems to be a little deeper.
"Immigrants will be carefully integrated so as to cause the least disruption to the developed economies"
In Eu ? In EU internal immigrants may do whatever they want.
Don't countries have to meet certain economic benchmarks before they can join the EU?
Following the 1917 revolution, the ruling Institutional Revolutionary Party (PRI as a Spanish acronym) spent several decades attempting to implement communism but ultimately devolved into almost pure corruption. The election of Vincente Fox Quesada in 2000 removed the corrupt semi-communists from power. Mexico actually ranks among the richer nations of the world; however, several states, especially Chiapas and Oaxaca, continue to suffer from communism. Crime and corruption run rampant throughout Mexico, especially in Mexico City and the norther border regions. Mexico's northern neighbor is far more prosperous and powerful, so many oppressed, impoverished, criminal, or opportunity-seeking Mexicans cross the border.