Earlier quoted context omitted.
Picture, for example, a card which has a small OLED display which displays an amount and a merchant name. You press a little button on the card, and an authorization is generated, cryptographically signed with an embedded key, and sent to the card reader (which also provides the power for the card). Such a reader can be built into laptops, keyboards, smartphones, available as small stand-alone USB devices, etc.. Web…
Well, I can see why they haven't implemented that - its a huge undertaking to build specialized hardware like that into so much varied equipment. For all intents and purposes rolling out a system like that is impossible.
I'm curious, what other undertakings do you think are impossible? WiFi? Bluetooth? GSM?