The purpose of these machines isn’t to actually work as intended. These machines are here for plausible deniability: “we pulled you aside because the machine said so, not because you’re Muslim”.
Or the computer said he was lying about not being a terrorist, so we went to arrest him but he was not cooperative and violently resisted, which of course is what a terrorist would do, and thus we had no choice but to shoot and kill him. In self defense of course and to protect the public. This is OK because the computer determined he was a terrorist and computers don't make mistakes.