Usernames and passwords combinations have been in use for decades, previous and ongoing security breaches at major businesses result in millions of username/password combinations being stolen on a regular basis. To make matters worse many people still use the same password to access multiple accounts so once stolen multiple accounts are compromised.
Biometric authentication is less vulnerable because a user's biometric data is unique making it very difficult for an attacker to fraudulently replicate an individual's eye, voice, fingerprint or facial recognition scan.
With modern mobile devices biometric authentication only takes a moment and apart from being more secure than passwords it's usually far more more convenient.
