I think the reason why the 'catchphrases' for Siri and Google Assistant are longer is because the cost for false positives is higher. Phones are subject to muc

I think the reason why the 'catchphrases' for Siri and Google Assistant are longer is because the cost for false positives is higher. Phones are subject to much more varied conditions than a cylinder that lives on your nightstand. Anecdotally, I have seen Alexa activate incorrectly much more than Siri, I just care a lot less.