Really, the article isn't even that clear on that much.
It's not clear if this is something that the app is reporting to the driver, or something that's part of the camera software....
There's also the issue of people with, for example, Parkinsons, where they will have difficulty with movement that could be taken as inebriation.
It seems by being vague, they can test the waters as to how people would receive the idea.
Yeah great point, personally I already assume the worse as far as how much information is accessible to them. What they do with it is where we really don't know. I know you can find just about anything on the dark web ;)
Even in other circles there's probably more of our information being sold depending on what companies/gov projects need. Just look at what's happened to Facebook - there are some employees that left after realizing they created a monster of algorithms through the use of our divulged information..