And ".... hidden commands that are undetectable to the human ear to Apple’s Siri...

And ".... hidden commands that are undetectable to the human ear to Apple’s Siri, Amazon’s Alexa and Google’s Assistant."

And then "digital assistants like Amazon’s Alexa or Apple’s Siri are set to outnumber people by 2021".

Why is Google mentioned in one context but not other?

Dark times are ahead for Assistant. You must warn her of your discovery!