You are casting a very wide brush lumping all legal immigrants in with those in a program you mention. Most legal immigrants do not get government assistance or come here with their last dime in the pocket.
I have direct first hand experience on this subject. The requirements for legal immigration are costly, time consuming AND require the ability to show financial wherewithal. Legal immigrants are not allowed to collect social security until they have worked for 10 years.
Most legal immigrants come to this country, work hard (as in bust their butts to get ahead) and pay lots (and lots) of taxes.
You may have a particular problem with one immigration program but it is very unfair of you to cast all legal immigrants into that group. It is also uninformed. I certainly welcome you to correct me where I am wrong and I would expecially like to learn more about the programs you talk about that provide cash assistance to legal immigrants. My guess is that is for people claiming refugee status but again it is good discussion to have and I sincerely would like to have those details.