[prunebeads]

>think bags of groceries in both hands and you forgot to preunlock

If you've got both your hands busy, whichever keylock system is on your door is irrelevant. Only a voice activation system would be Ok.

[jordanthoms]

Lockitron can unlock based on proximity to a Bluetooth 4.0 phone

[gigantor]

I practice (though uncomfortably) I am able to extend at least two fingers, enough to enter a 4 digit code and turn the knob. Unlocking vie the phone with two grocery bags is not so easy.