So every country in the world should simultaneously roll out this $2 2FA token?
And the governments of the world are going to do this is an anonymous way?
Who is going to manufacture these 8 billion (Or at least 3 billion if we only count Facebook's MAU) tokens?
And there still needs to be a global database of valid identifiers, else anyone could just create a software token that they can reprogram ever second.
And we expect all people to carry these 2FA tokens perfectly?
And what happens when someone looses this token? The post office has way to prove you owned that token in your proposal.
Same thing for revoking a token. There is no identity out of the token, so how do you revoke it after it is lost? People are not willing to store a piece of paper in a security deposit box.
This "easy" solution is impossible in practice.