Comment Two out of three.... (Score 1) 70
"We use locks on our doors to keep criminals out not because they are perfect, but because they are both convenient and effective enough to meet most traditional threats."
There is a third reason that such locks are practical, and it is something that cannot be satisfied by any kind of biometric authentication.
Failure of the security system provided by locks, however infrequent, can still be mitigated enough to carry on with no less effectiveness to meet security threats in the future as you had before the failure. IE, you can go ahread and change a lock