https://en.m.wikipedia.org/wiki/Reasonable_person
You have no expectation of privacy in a public space, and the courts have agreed with that many times
As an example:
http://resources.uscannenbergmedia.com/2016/08/videotaping-a...
"Remember, even if you’re in public, you cannot record conversations between two people unless you have their permission. This includes conversations that you’re one of the parties to. If one person in the conversation can reasonably expect his or her conversation to be confidential, this standard applies."
If you're having a private conversation in a public park, then it is probably illegal for somebody else to record you.
Driving is a different question. Personally I think since a license plate is literally meant to publicly identify your car, a reasonable person should expect it to be recorded. But my guess is this will go to SCOTUS at some point, since privacy is increasingly being invaded in unanticipated ways by private companies.
our goal isn't to build a big-brother system. we believe that if you are on a public road there isn't a perceived expectation of privacy.
If, for example, these gadgets, or existing security cameras started to pool their data, run (accurate) face-detection on it, and start publicising everyones' location history online, I'm pretty sure most people would object to that–even those that previously had no problem with their image being recorded by the CCTV at the gas station, or the tourist taking a photo that included them.