By 2026, almost $5.8 trillion in payments are expected to be made using biometrics each year, according to a Goode Intelligence forecast.

The latest example comes from California. Biometrics fintech firm PopID invited scrutiny at a student event at the University of Southern California (USC) campus in Los Angeles after leaving no choice to purchase food inside the venue aside from its facial recognition payment system PopPay.

"[It's] slightly coercive, because you're not really being given a choice between normal payment methods and using your face, which is a pretty intimate subject matter," USC student Vera Wang told student paper The Daily Trojan.