Apple sold the public on the ease-of-use and reliability of the Touch ID, then they applied it to payments. It will be multi-factor, but not using the two traditional factors (something you have, something you know). Instead, it will be using something you have (the phone) and something you are (an authorised fingerprint). The remarkable part of this plan was getting the fingerprint biometric adopted by millions of users first. Once that hurdle was cleared, adapting it to payments was a straightforward exercise built around years of experience with biometrics.