I disagree with them, generally people expect that where they drive isn't being tracked.
They can't drive somewhere thinking that no one knows they're driving there?
That's the point of the clandestine tracking, trying to find them driving somewhere incriminating thinking no one knows, 'expecting privacy' about where they go.
It's pretty hard to infer the founding fathers who said you can walk down the street with a box of incriminating evidence and be protected from search, would say that secretly tracking everywhere you drive would not violate the right you have to go somewhere without secret tracking.
On another note, though, law enforcement does seem to have the right to blatantly follow you in a more expensive manner, using agents who can follow you everywhere you go in public. This technique was used by Robert Kennedy to intimidate a top mob boss, as I recall.
It's not a black and white issue, though. When you do drive somewhere, it is a public activity that you are vulnerable to being seen doing, not 'private'.
So you have this choice between saying it's 'protected' and 'inventing' a constitutional right for going somewhere in public being 'private' as a permanent constitutional right prohibiting who knows what for law enforcement surveillance, and not saying it's a right and allowing for intrusive secret monitoring without probably cause apparently. Neither is too attractive, but I can have some reluctant sympathy for the court saying that this does not fall under constitutionally protected rights.
It's great to see the Reagan appointee concerned for the poor, but the rich do get some advantages. If a rich person can afford to have a random rental car when he goes out, he might evade the gps. That comes with being able to do that, and doesn't change the constitutionality of the tracking for those who can't afford it.
This is a ruling that has some shock and offense as a reaction, but when you consider the law, has less basis for objection.
I've wondered when the government will have standard gps put into cars (like seat belts) that they could do this with for anyone all the time.