The GPS can provide more than what can be obtained with a tail.
Plus there is the “physical intrusion in attaching the device”.
I don't think so, like what? GPS data is a stream of (location, time) pairs. Exactly what a tail can record. The only potential problem would be obtaining location on private property where aerial surveillance would not penetrate. But in most of those cases the GPS would not either.
Plus there is the “physical intrusion in attaching the device”.
That is an interesting angle. Will have to read the rulling to see what they say about that.
“physical intrusion in attaching the device”
Bingo. The reason the justices were unanimous was that in order to use the GPS tracker, the police had to “trespass” on private property, namely a privately owned vehicle.
Also, the justices were very concerned that there was no time limit guidelines on the search.
Again, if you have probable cause, get a warrant.
Regarding the phone company, we have a lot of people that get lost out in the mountains. The phone company has greatly speeded up emergency access to cell phone triangulation to less than an hour.