The court argued that a car is so public and visible that the GPS tracker is only collecting "public knowledge" anyway.
[0] https://www.tagesanzeiger.ch/panorama/vermischtes/wenn-am-au...
We specifically use AIS [1], tracking ships is quite easy because of it. Other methods are radar.
Because it so relatively easy, there are a lot of commercial companies doing it too. The most well-known is probably MarineTraffic [2]
[1] https://en.wikipedia.org/wiki/Automatic_identification_syste...
Enforcing an prohibited zone, which exists for safety, probably is well within parameters. If you only track and save the vessel that are very close to your drilling platform because you can't track a persons movements from just that data.
If you go to a public concert, people can look at you, note that you were here and tell that to others. That doesn't violate privacy because you had no privacy there to begin with. And in a similar manner, if you drove last thursday on a particular road, whoever bothered to look at you and your car is allowed to do so, note that you were there, write it down and tell that to others.
Privacy is about your private stuff - what you do in your private space, what you have in your private items. If you go out in the public, the things that you do (and where, and when, and with whom) are not private anymore.
I work for a semi-governmental organization in the Netherlands and we track ships. Tracking company-owned commercial ships is no problem, but we are heavily restricted by law in what we can do with the location data of privately owned ships because people live on them.