Most of the time, you're absolutely right especially with how Octave or Julia code is normally distributed. The code is delivered to the client and the client runs the code on their system. No GPL violations have occurred.

That said, I believe it gets trickier once we start compiling the code. Say I want to develop a piece of software for my client and I don't want them to have the source, Octave doesn't really have a way to do this, but MATLAB does and since MATLAB has purchased all of the requisite licenses, we're good to go. Julia makes me more uncomfortable. We can make binaries with PackageCompiler.jl, but if we do, we should be subject to the provisions in the GPL. That's no different than any other piece of software, but Julia, Octave, and MATLAB all use these libraries and most people don't know that something like the chol command hooks into SuiteSparse in the backend.

Yeah, the Julia devs are quite interested in removing our last few GPL dependencies and replacing them with something in pure julia. It'll take time though.