Re: They will never work in an urban environment.
"..... whereas holding up a robot car would be like swearing at the self-service till in Tescos; everyone does it, nobody feels bad about it."
I don't, ever, and I would were I to.
I know machines are far, far less sentient that fleas, sheep or politicians but I always say "thank you" to ATM's and other robots doing me a service.
I've even been known to thank the washy machine and my microwave.
Being nice to a robot car would only be an extension of my normal politeness.
I'm polite to cats, moths, dogs and many humans, too.