Biometrics could eliminate the need for any form of tactile card or other authentication system, and of course, work everywhere. A fingerprint and/or eye recognition system would take up little space in a retail or travel location and allow transactions to be carried out securely and quickly, with no risk that the customer would lose their ID or payment method.
Why are we skirting the issue? The technology is already built into the iPhone 5S, Samsung Galaxy S5 and various military establishments, so why not public locations? What is hold this back? Cost? Reliability? Is there a security issue we're not being told about? Etc.