I agree with you. There is a utopian ideal and then there is the reality of the present. SS numbers have been used for decades now, and if they are good enough to use for legal citizens then they are good enough to use to help find and deport criminals, and prosecute those who aid and abet those criminals.
Absolutely. Until the day 3rd world nations either rise to our level, or we lower to theirs, the libertarian open border notion is just a pipe dream. We just have to much to lose.