Irrelevant- you "report" the car license plate to an independent service, and the driver of the car can look up if they were reported or are alerted they were reported if they have the app installed. At least, that is what I understand of how it functions. Doesn't really do much to stop the driver in my opinion nor does it do anything to alert the police of a reckless or drunken driver. I prefer the old reliable method of dialing 9-1-1 to report a dangerous motorist on the road. The app is cute, but I see no real benefit to it.
I hear the secret business model of apps like this is (there are others), that they then resell the data to insurers, who may raise the reported drivers rates. No legal repercussions possible, but still sounds good to me.