Originally Posted by
jwmw
When you enter the US via a US Airport you will use Global Entry Kiosks with your passport, and your fingerprints are on file for this reason. If you're using a Nexus kiosk at a US Preclearance the above procedure will apply. The important thing to keep in mind is that No matter what country you're entering the iris scans are no longer used.
The GE Kiosk at Pearson uses facial recognition now. I didn't need to provide my prints.