No, you are right. Law enforcement may have a problem justifying attaching a tracker while the vehicle is in private property, but any place public is fair game, I think.
It is not about me, I won't be putting any trackers on your car. Btw, J Edgar Hoover would have love this ruling, and he was a staunch anticommunist. So your analysis is flawed.
After reviewing Kyllo v. US, I think this ruling allowing law enforcement to GPS track a suspect without warrant may be overturned should it get to the supreme court. It will depend on the location and target of the GPS tracking is initiated, whether on private or public property :