That's just one that comes to mind. Anywhere that has positive ID would work. Which if we account for data brokers can potentially include anywhere you use a credit card. (Yes that will not be a perfect 1 to 1. Obviously that doesn't really matter in practice. LE is used to dealing with lots of noise.)

But suppose there's no hit. That's a hit in and of itself. Someone just needs to have the idea to have the software that ICE agents use flag anyone who fails all recognition methods (facial, gate, etc) because it means they haven't been through an airport, haven't crossed a border in a legal manner, don't have a passport, and don't show up with any of the data brokers.