I was talking with some people recently about self-driving cars and how one day you'll be able to pull your phone out of your pocket and order a taxi, and it'll show up just like an Uber car, only without the driver in fact, Uber's working hard to ditch all of its human drivers .
We adjust our habits or actions in light of both strangers' awareness and our own awareness of their awareness...even if we don't realize we're doing so.
Of course, these future autonomous taxis will probably have more than a couple varieties of deterrents: perhaps a security camera that monitors everything you do, the threat of paying handsomely for any damage you're proven to have caused, and the public shame of being blacklisted from a particularly popular mode of transportation.
Who cares about potentially paying damages if you're registered with a limited-funds prepaid credit card and under a fake name?
If cartoonish printed eyes on a sign can deter littering, can a pair of life-like eyes somewhere inside an autonomous car keep bored or otherwise destructive people in check?
Or, in a less draconian fashion, manufacturers may choose to distract their riders into peaceful obedience with on-board VR headsets and built-in movie projectors.