[mdaEyebot]

Sure, but computer chips are probably the most complicated things that our civilization can currently make.

Asking somebody to prove that a computer won't do X is a fool's errand, outside of some shrinking safety-critical industries.

That said, you could always make your own smart speaker with a hardware button or shell script instead of a wakeword:

https://developer.amazon.com/en-US/docs/alexa/alexa-smart-sc...

[im-a-baby]

That's very different than your initial statement of: "Many schools of thought believe that it is impossible to prove the absence of something.". Many (all?) schools of thought believe in the law of excluded middle, which makes it possible to prove the absence of many things.