Nobody declares our rights, we feel them in our guts. And the public feels this one in their gut without me having to explain it, which is why I call it a right: If something is generally accepted by the public, it is a de facto right. For example you could repeal the 1st amendment tomorrow but that wouldn't change anyones mind about whether freedom of speech is their right. But if you want me to stop being pedantic and actually defend my position, I would argue that people should have this right so that spammy AIs don't just ruin human interaction all together. Imagine a world where you never know if you're talking to a real person or some kind of AI trying to sell you something subtly... Not knowing explicitly whether you're talking to an AI or a real human could have a chilling effect on human-to-human relations.
Now google duplex can go and phone up every businessowner asking for the current store hours (or whatever), thus dumping the work of updating google's information on the store owners at essentially no own cost.
And the store owner does not even have a chance to find out whether it is a customer that will in some probability show up, or if he's just being used.
'Dear turing test candidate, how would a program to do this and that look like.'
Or 'business strategy'.
There are real threats to the transition though. My honest fear is that the people who discover it make themselves immortal gods and subjugate or kill everyone else.
Subjugation already happens. When it's easier to keep the population poor and just raid the natural ressources of a country, that's the way it often goes.