Android has per-app microphone permissions that you can disable, if you want. At least in theory, Google apps honor these permissions, and on LineageOS, you can verify that this is the case - while with the Alexa, not only is there no way to audit any of the code running on the device, but it's explicitly marketed as being always listening.
Oh, this is true - although the likelihood and ease of it being exploited as a listening device are much lower than that of a device explicitly designed to do so.
Edit: Not to mention that the entire Alexa is a black box, too.
Second Edit: Not trying to claim that you're an idiot, just provide some perspective.
