Not always, instead the Smart Card accompanies the password and even other authentication means.
It's like this, a Smart Card is "something you have", like a badge. Of course somone could possibly copy it or steal it. So add it to a password, which is "something you know", and you add a second layer of security and help minimize the weakneses of each. Lastly you can add other factors, like biometrics, "something you are". A fingerprint or iris scan can act as a third factor again increasing the depth of your security while minimizing the weaknesses of the others.
Now that makes sense...though I still imagine if we move to Biometrics, Jack Bauer will cut my thumb off or kill me then steal my eye