Earlier quoted context omitted.
Do you really propose a manufacturer like Apple is going to grant continuous access to the GPS receiver in their phone to the providers?
I am not sure what you are asking. In the OP article they plot each point so that you can see them explicitly. They then mention these are GPS points. Cell triangulation needs no client side data; it uses only signal strength and three or more towers.
So what is the connection between the GPS points and the cell triangulation? How does having the cell triangulation data lead to having the GPS points? The parent claims the providers can magically access the GPS receiver in the handsets. But they really cannot, so the providers only have coarse data that cannot be used to track people on this level. The data is from another source, not the provider.
It’s much more likely the user agreed to install an app that is recording his location information.