there is no friction:)
simply they are very protective with their artwork and only in few cases they let others use them, its their policy. A lot of time ago others asked permission to use their models in fs2 with negative response, and i think that GE asked again with same result
if they will change their mind we will surely be happy to use their artwork
personally i disagree with this point of view, i can understand a company to be protective with his own work, but with non pro artwork not only i think that being overprotective is useless, but also i think that it is a proud if others ask you to use your artwork(with some limitations obviously), because it means that you have worked well