Apples Touch ID fingerprint identity sensor is not able to provide a high enough level of assurance that the person using the device is the same person authorised to use an application. Apple has no concept of a fingerprint belonging to an individual user. If a device is shared, any user can add a fingerprint to Touch ID. If unauthorised access is obtained to the device (by guessing or otherwise obtaining the passcode as opposed to an opportunist accessing an already unlocked iPhone or iPad) then the user can also add their fingerprint for later use. Sensitive applications such as banking applications should not use Touch ID as the only means of authentication.”]
Source: https://informationsecuritybuzz.com/articles/when-the-cost-of-convenience-is-compromise/