Because a country can't function if money isn't being put in to it. People who are citizens have to pay taxes, and they put money back into the economy when they buy things. Most illegal immigrants come in, not registering, or not trying to become a citizen, and take money out without putting money back in. They send money back to families in other countries, because they can get more money here for less work then they can in their own countries. And they don't have to pay taxes.
Thalia: that is a different type of imigration. That is legal. It still is that way, people do it every day. People came in, and registered as citizens, there by taking on all american responsibilities, taxes included. That is one of the basic values of american exceptionalism. Legal immigration. But when someone decides to come into the country, live here, not pay taxes, and not be a citizen, WE pay for them. It would be like if i came into your house, and took your lamp, and walked out. As apposed to knocking on your door, and nagotiating for the lamp. BIG DIFFERENCE.