1. My wife can check that we didn't forget to close it instead of driving 20 minutes back home to quell her nerves.
2. We can let a friend or neighbor into the garage (or into the house if we use the smart lock on the door inside the garage) when we're not home. Without giving permanent access to a key or PIN code.
Seems like a bit of an ill-adaptation. I used to want a smart door lock for exactly this reason, but instead I learned to be mindful when I close my dumb door...
Also many smaller smart home device manufacturers with an app seem to be heading in the direction of wanting to expand into other smart home devices and lock you into their proprietary ecosystem, while the rest of the industry simultaneously seems to move towards more interoperability via things like the Matter protocol, presumably to make it easier to interact with various voice assistants without requiring an individual gateway for each one.
This is just another reason to distrust any smart home device that doesn't support ZigBee, Matter, or a similar purpose-built local protocol.