Why people who travel like them
When you fly out of the airport down the road, the house key is one more thing to keep track of, and the spare under a planter is the first place anyone looks. A smart deadbolt replaces both. The door answers to a code or to your phone, and on a connected model you can check from the terminal that it actually locked behind you.
While you are away, a neighbor who waters the plants or a sitter who feeds the cat gets a code that is theirs alone. When you land, you delete it with a tap, and nobody has a copy of anything to hand back.

