And, of course, the lock can’t be accessed by businesses other than Amazon. No Walmart, no UPS, no local dog-walking company. Keeping tight control over Key might help Amazon guarantee security or a better experience. “Our focus with smart home is on making things simpler for customers — things like providing easy control of connected devices with your voice using Alexa, simplifying tasks like reordering household goods and receiving packages,” the Amazon spokeswoman said. But Amazon is barely hiding its goal: It wants to be the operating system for your home. Amazon says Key will eventually work with dog walkers, maids and other service workers who bill through its marketplace. An Amazon home security service and grocery delivery from Whole Foods can’t be far off. (Walmart has announced plans to test delivering groceries straight to the refrigerator with a smart lock maker called August.) Amazon said it doesn’t have access to data about when you lock your door or the video feed from the Cloud Cam — both good things. But surely its data team is also crunching the numbers on how Key changes your consumer behavior, especially whether you are buying more stuff from Amazon.