Immigration & Customs in almost all countries tend to be despicable in general. It's harder to get accountability from them, since the people they lord over tend to have no voting powers.
It's too easy to single out these agencies in a hatefest.
It's like hating the policeman because they keep busting you for drugs. It's not his fault they're illegal. In fact, many policemen feel the drug laws are stupid. It's equally likely that many in the INS feel the law is unjust. What are they going to do, though? Break it?
Responsibility flows upwards in such matters, especially where governmental mandate is concerned. Blaming officers of the government for merely enforcing the will of the people is misguided.
(1) Doesn't count for non-democracies, obviously, but even in those cases they'd just be enforcing the law of the land, with little individual perogative.