To answer your questions:
1) Why? Faster than keys. And I might forget my keys, but I won't forget my phone. Also, if a neighbor wants to borrow something, I can let them in remotely and lock the door behind me.
2) No, but I often am not sure if I locked the door or not. Or see the above example with a neighbor.
3) I don't see how that's relevant. If I'm home, I'll walk over and open the door. Or if they yell "It's John!" then I'll open it for them.
4) Nope, not in my apartment. And at my family home we never used the knob lock, only the deadbolt.
2) No, but I often am not sure if I locked the door or not. Or see the above example with a neighbor.
3) I don't see how that's relevant. If I'm home, I'll walk over and open the door. Or if they yell "It's John!" then I'll open it for them.
4) Nope, not in my apartment. And at my family home we never used the knob lock, only the deadbolt.