bj229r,
Those numbers didn't match, so the money stayed in the government coffers. No refunds go out for those, that's why the government is not truly interested in enforcing work rules. They encourage illegal aliens to use the taxpayer ID number system by saying it "may" lead to citizenship or legal status. It doesn't lead to anything except the government getting more people not paying taxes through withholding to pay taxes. The IRS only cares about collecting money. (I know that may not come as a big surprise...)
The point here is that they are paying taxes in greater and greater numbers. Reagan started the amnesty bandwagon and it's happened a few times since then. Millions of illegals suddenly became legal, but that didn't change their economic status.
They weren't talking about the same people at all. That is a crucial part of the misinformation. "Criminal aliens" include resident aliens, temporary workers and illegal aliens - all of them. The immigration rules tightened several years ago. The only people allowed to immigrate now are the cute and furry ones - the ones with degrees and money. Before that, most were poor, without strong language skills and without as much education. How successful do you think you would be going to another country without any money, language skill or education?
Poor people go to jail more than middle class people. That accounts for some of it. You don't see many programmers, doctors or engineers from India in jail.
Once again, only illegal aliens can be arrested for immigration offenses, so that skews the numbers, too.

It's too bad you can't require every illegal alien being deported to take 3 American prisoners back with them. That would really clean things up.