Well, that’s not quite true. It’s one of the reasons they don’t need a warrant to search your car compared to your home. Because it is mobile and moving around public spaces, your car doesn’t have nearly the same level of privacy expectations as your home.
I seem to recall the article specifically mentions that the data is not retained. In fact, the law wouldn’t allow them to retain any information. They are also not tracking anyone. It’s no different than a cruiser parked on the side of the road that you happen to drive past.
If you raise suspicion, that officer is more likely to retain information about you than what that computer system is doing. Try erasing his brain 
When I was younger, I had a propensity to get a little wilder at times driving the same route to work each day. Got pulled over once and the cop basically had watched me pushing the limits on more than one occasion before pulling me over that day.
If they are specifically interested in knowing where someone in particular is going, wouldn’t it be easier just to follow them than store a single point along their entire trip? I just don’t see the value in it…