Is respecting GPL too complicated?

I've had a bunch of hunches recently about companies abusing the licensing terms of Dokeos by officially declaring (but only verbally so far) that their product (being Dokeos, but not officially) is not open-source software. The GPL licensing makes it clear that the software derived from GPL software, or any alteration to a GPL software *must* be open-sourced, at least for the people it is distributed to.