Many new immigrants to the US have been quoted - when asked why they wanted to come the the US - "I wanted to go to a country where the poor people are fat."
charity is one of the best exemptions, it is better for private interests to determine who is worthy of help than government/political hacks.
This sounds like total cherry picking and I don't believe for a second this is why new immigrants come here. They come here because of absolute lack of opportunity or forward outlook in their own countries not to exploit the system. Heck the vast majority of "illegals" who arrive here work insanely hard - harder than most Americans - in order to just survive.