Again, biometric data is unique to each of us and is verifiable at each check point. Like computer workstations that need thumbprint scans to log in. Of course they can issue visas, and the biometric gets put into the database, and we can track who they are, that is the point. At any check point when a set of biometrics turns up that we are on the look out for we can ID him. So what if they have to pay to get a visa to cross mexicos southern border. If its a terrorist, we can track and arrest him now. Your arguments make no sense.
No, you're making assumptions about the extent of existing databases, vs. existing thugs and terrorists.