Why don't you go back?

Why don't you go back to your country to make it prosperous? That's what someone yelled at a person that took the microphone in a protest against the SB 1070 in Washington Square. The person in the microphone hesitated and then answer that maybe some of us need to go back and make our countries prosperous. Maybe that is a question we (Latinos living in the US) have to ask ourselves but it's a question Americans have no right to ask.
How an American asks an undocumented worker to go back to a country impoverished as a consequence of following policies imposed by the US? Why Hispanics have to go back and the Europeans that came before us get to stay? Why none of them went back and make their countries prosperous? Why Latinos have no right to enjoy the fruits of our labor? Undocumented workers work sometimes harder than Americans. It's their hard work and low wages that made this country prosperous. What's Americans merit besides being born here?
Some Americans think that because undocumented workers came to the US breaking the immigration laws they don't have any rights. It's surprising that Americans and Latinos alike never mention that undocumented workers break this laws because they have no other choice. They have no other choice because their countries are poor because they follow the policies that America imposes on them. Nobody mentions that many farmers, fisherman and truck drivers lost their jobs in Mexico because after NAFTA they had to face unfair competition and fight against unfair laws from the US. Nobody mentions that if they don't want us here they have to stop making our lives miserable back in our countries or at least let us to make our own mistakes.