Not very handy in the case of a stolen purse or a break-in if your phone is also gone.

Hopefully your app is already set up and doesn't require access to the key to do so. It also doesn't account for dead a dead phone, dead car battery, or no cell service.

My method is free or inexpensive and works without any outside tools or assistance. It's so much more adaptable and foolproof that it's a no brainer for me.