Amazon offers several new surveillance microphone products, meant to be carried around by people during daily life. That will enable them to listen to whoever the device's "owner" comes near.
But don't worry — Amazon is learning how to talk the talk about privacy in a way that more people would find comforting.
A voice command system that is safe for its owner would be one that runs only free software, and does the whole job locally, communicating with other sites only when asked to. With the software inside free, the owner of this device would truly own it.
But even that would not respect the privacy of other people nearby. How to deal with that issue is not obvious.