All the comments so far have been focused on why it won't work or will be a problem (I'm not counting the snarky ones.) How about you geniuses come up with workable suggestions? I've thought for years that we need a trust based system. Every method for authentication is fallible and hackable, so we need to use a mix of them. Every time my face is on camera (red light camera, store security camera, the web cam two cubicles over...), it should be verified that I match previous facial recognitions. Every time I speak any microphone within range should authenticate my voice. Automatic tracking of my cellphone and car should contribute. One very important factor is location tracking - if I am at work I can't be authenticated at the gas station unless enough time has passed for me to get there, even if my credit card is swiped. Every validation of my identity should raise the trust level, and it should decay over time so new authentications need to be continuously collected. That way passwords can contribute, but using one in the wrong place or time when I am demonstrably somewhere else will be denied and noticed. Yes I can still buy stuff over the net with a credit card, IF authentication says that request came from a device I am using AND I provide another token (i.e. password) or verify that purchase on another nearby device, raising the trust level in my location and intent to purchase.
As long as it has a short-term and long-term memory, trust based authentication like this can handle the variations in humans from catching a cold or encountering a life-changing situation. Truly, location tracking with decay and continuous updates contributing to a calculable level of verifiable identity is the best we can do. Funny to say, but it is no longer black and white in this digital age.