Comment by larkost
I think this is mostly because they don't care about false-negatives. They have forgotten the idea that our justice system was supposed to hold true to: "better a hundred guilty go free than one innocent person suffer" (attributed to Benjamin Franklin).
This can be seen in the case of ChongLy Thao, the American citizen (who was born in Laos). This was the man dragged out into freezing temperatures in his underwear after ICE knocked down his door (without a warrant), because they thought two other men (of Thai origin I think) were living there. The ICE agents attitude was that they must be living there, and ChongLy was hiding them. That being wrong does not cost those ICE agents anything, and that is the source of the problems.
Do you mean false positives? A false negative would be "we checked to see whether Alice was in the country illegally, and the computer said no but the actual answer turned out to be yes".