This is fairly classic engineer thinking and what I was referring to in my comment below.. you can wrap a GPL library in its own program, put that program on a separate VM on a separate physical host in a separate physical building, talk to it only over a network interface and your program's resulting interaction with it might still be construed as linking.

Similarly, your program might statically link against a GPL'd library, but only pass bulk data through a programming interface in a coarse manner, and the result may not be considered linking. The FSF FAQ even explicitly addresses this case.

GPL leaves these kinds of mechanisms blurry and ill-defined (I presume intentionally), it's just that as engineers we are commonly only taught how violations manifest in the usual case.