You can completely disable Siri or whatever your device's equivalent is. The entire purpose of Alexa is to be listening all the time. They're not equivalent.
Can you prove that you've disabled it? That it's not listening all the time and logging interesting sounds?
I don't see a huge difference between a speaker that's designed to have an always-on mic listening for a code-word and we're just going to trust that it doesn't log anything unless it hears that codeword, and a phone that's designed to have the same, but has a software option to turn it off.
Either way, we're trusting that the device isn't abusing the fact that it has a mic.
No, I can't prove that it's disabled, but that doesn't matter much. There are people out there who probably could and would be more than happy to publish their results if they did.
More importantly, the difference is in intent. I don't intend to carry around a device that's always listening to me. Anyone with an Alexa device is intentionally inviting Amazon to listen to every word spoken in (part of) their home.
It is always listening. A coworker has Siri enabled and it regularly interrupts meetings because it thought some random noise was a wake word. It then proceeds to do whatever Siri does, which I assume involves sending whatever it hears after that point back to Apple.
I carry around and iPhone where I've done my best to completely disable Siri so I expect it not to be listening. That's antithetical to the use-case of Alexa and similar devices.
But the intent isn't there for Amazon to listen to everything you say - which is why hotword detection is done locally on Alexa and only then is an audio stream sent to their servers.
I have a coworker who has Siri enabled on his phone. It regularly wakes up and starts recording seemingly at random. Maybe "always listening" isn't the correct phrasing. "It might be listening at any time" might be better.
