I think you're expanding frustration at telemarketing to this technology, and I don't understand why. It's not an "autodialer;" it doesn't appear to have any kind of multicast capability.
I think Google could avoid a lot of these concerns by providing a quick and universal opt-out -- robots.txt for your phone? But the most scientifically impressive part of the AI, its inclusion of human quirks of speech, are exactly the opposite of this: an effort to evade detection.
That's not a very compelling argument, though, because as long as those reservations manifest as people arriving and paying bills, they're unlikely to find this a problem. And as long as the calls are essentially the same as a human calling them, it's not that different.
I think a lot of people in this conversation are conflating annoying phone calls with robocalls. The problem with annoying phone calls isn't that they are automated... the problem is that they are annoying. If I got the exact same phone calls, but they were all staffed by humans, I would still be annoyed. The automation just means they can make the calls faster. A restaurant owner is not going to get particularly annoyed if a few reservations come in from a bot rather than a person calling, as long as the system works correctly (i.e., can take "no" for an answer for instance) and they aren't hammered with ten thousand calls in an hour due to some bug. When I get a robocall reminding me about my dentist appointment, I don't go ballistic and yell at my dentist for using bots... after all, I asked for it by clicking an option in my reminder email. (Given that I've forgotten my appointments a few times before I'm not in a moral position to be upset that they have some reminders set up.)
The problem is, the restaurants (etc.) don't get to choose whether to take the risk, even though they stand to bare most of the cost. That's an ethical problem before the product gets released. After the product is released, it's a problem with incentives: if consumers make the choice to use Duplex, growth means adapting to their needs, not the recipients.
How does that differ from just basic economics of being where the customer is?
Restaurants installed phones to be reachable.
Restaurants contract with web service providers to be present on the web.
Restaurants locate near available parking or buy additional land to convert into parking spaces so customers who do not walk or use mass transit can patronize them.
Restaurants get involved with systems like OpenTable or their own online booking solution to be maximally reachable to their potential customers.
If anything, this system has the advantage that restaurants have to change almost nothing about their process to be involved with it, relative to the years of previous technological changes they've adapted to.
Maybe we disagree about whether opening a phone line is opting into be called by a robot. I don't think almost any restaurant thinks of it that way, and if they did then it wouldn't be necessary to fake human vocal inflections when you call them.
The view you're expressing is what reminds me of telemarketing -- it's a presumption that the fact I open up a channel means I've authorized you to do anything you want with it.
Regarding your parking lot analogy, I think we're going to have exactly these arguments about usage of public space. Will stores with counters be ok with Drones flying in to stand in line? Stay tuned!
If you are, why may I not presume you're comfortable talking to a robot assistant?
If the experience of talking to the robot is noticeably degraded from the experience of talking to a human, that's a different question entirely---I'm assuming they're equivalent, maybe I should not. But if they are equivalent, what is the difference to the business owner?
(And FWIW, I think the drones would likely drive or walk in; look for Segway or Boston Dynamics to come up with something in the not too distant future ;) )
For me, the core question is who gets to make that assumption, not whether it's correct or not. The people who are most impacted by uncertainty should have a choice about participating IMO.
But, one thing I'm realizing from other threads is that some people feel they have a similar level of uncertainty for human interaction, and are frustrated by the status quo of needing to interact with services. For me, that says this tech clearly has a place -- it just needs some effort to proactively establish etiquette around it's use.
So, y'know, they should probably not do that. ;)