It seems that as more people are realizing the trade offs between convenience vs surveillance with digital assistants these devices are becoming more private than even just a year ago. People are getting concerned and manufacturers are starting to listen and build in more privacy tools.
Fundamentally, in order for Alexa to get better at understanding voice commands and acquire new skills it has to learn from real-world data. In certain cases the actual voice recordings has to be used to transcribe and compare accuracy.
For a long time I've been holding out on getting Alexa specifically because I worry about my privacy. But a few months back I decided to get it for convenience while cooking in the kitchen. I felt that the conversations I have in the kitchen are very benign and even if recorded and heard back by another human, wouldn't really invade my privacy:
Now it seems like Alexa is adding abilities to delete any recordings on the day and newer devices are even shipping with physical blinds for the camera. So the trend is moving in the right direction, though I wish it was faster...