The rental car we picked up on a recent trip was bright red, had push-button start and a smart key. A smart key looks more like an oversized thumb drive for a computer than a key with teeth. We drive old cars with keys with teeth, the kind you put in the ignition and have to turn with your hand. (Oh, the exhaustion.) Settled at our destination, I met with a book editor at a coffee shop. After a delightful chat, we went our separate ways. I rummaged through my bag and my pockets and couldn’t find the car key anywhere. I glanced in the car and saw it on the passenger seat. I had locked the smart…